PLANO, Texas — There was some desperation in the air at the indoor mall where Shein had opened a pop-up store.

A security guard posted at the entrance said that on each of the three days the pop-up was in business, he’d turned down about 20 bribes from people looking to skip the line. Often they offered $20, he said, though some went as high as $100.

On Sunday, the last day, the first shoppers arrived at about 6 a.m. Shein was scheduled to open at noon. The line swelled throughout the morning, folding in on itself before unfurling through the food court, past the bubble tea stand and Mediterranean grill. Anyone arriving after 12:30 p.m. was advised to go home — denied the chance to buy, in person, things like $1 daisy earrings, $4 bucket hats, $12 cable-knit crop tops, $13 faux leather baguette bags and $29 neon PVC mule sandals.

“We had to take the numbers off the window,” said the guard, Don Dickerson, pointing to where a white decal displaying Saturday’s closing hour, 8 p.m., had been peeled off. Low stock had closed the store at 4 that day.

The enthusiasm was a sight to behold, considering that many shopping malls have struggled over the last decade to draw such a crowd: about 700 people waiting outside a whitewashed storefront formerly occupied by American Eagle Outfitters, sandwiched between Swarovski and Bath & Body Works. On Friday, the first day of the Shein pop-up, a man proposed to his girlfriend in front of the entrance.

“I was really nervous, and I wanted to surprise her,” said Nehemiah Jaime-Vega, 23. “She loves Shein.” His fiancée, Michelle Alvarado, 22, nodded. “It’s so affordable,” she said on Saturday afternoon, after her second consecutive visit to the pop-up. She wore a red ribbed-knit tube top, sold by Shein for $7.; she said she places orders about twice a month.

These pop-up stores are not how most people interact with the brand. So far, in 2022, there have been only five held across the United States, Shein’s most valuable market. But the pop-ups are part of an effort to make the Chinese fast-fashion company seem less mysterious. Shein — officially pronounced “she-in,” though often pronounced “sheen” — recently surpassed Amazon as the most downloaded shopping app in the United States, according to analysis by Sensor Tower. Shein is privately held and declined to share financial figures but was estimated by Coresight Research to bring in $10 billion in revenue in 2020.

Yet as Shein has grown, so have questions about its practices. Shein frequently makes headlines for its controversies, like selling a $2.50 swastika necklace or copying the work of designers. (The company said it takes infringement claims seriously, requiring suppliers to certify their products don’t infringe on third-party intellectual property.

Shein has also been accused of working with suppliers that violate labor laws, and failing to make necessary disclosures about factory conditions. In response, the brand pointed to “regular internal audits” and a “strict,” legally compliant code of conduct for its suppliers. It has also contracted firms including Openview and Intertek to audit its facilities; “when violations are found, we take further action, which may include termination,” the company said.

Last year, a CBC Marketplace investigation found elevated levels of lead in some Shein products, like a toddler’s jacket and tiny purse. Shein said it regularly tests products, following international regulatory agency standards, and “violations are immediately remediated.”

All of this has contributed to Shein becoming an archetype of a certain genre of supercheap clothing companies: It is the leader of a pack of Gen Z-favored brands, like Fashion Nova and Boohoo, accused by critics (including those from Gen Z) of contributing to overconsumption and waste.

Shein, however, called its approach to producing clothing “transformative”: It starts by ordering small batches of clothing (100 to 200 pieces) and monitors customers’ response to those batches before placing larger orders.

Still, many of the videos on social platforms made about Shein — including the incredibly popular “haul” clips, which show people trying on their large orders, piece by piece — inspire comments raising these issues: How can a $4 top be made to last, so it doesn’t end up in a landfill? How can the workers who sewed and shipped that garment be compensated fairly?

Yet this hasn’t deterred Shein’s devotees, many of whom feel they haven’t seen enough evidence to stop shopping with the brand.

Ann Taylor, a 25-year-old budding fashion influencer in Toronto who has received gift cards from the brand, sees those kinds of comments on videos “all the time,” she said. Most often, she has noticed, they raise concerns that the company is violating labor laws.

This summer, viral TikTok videos purporting to show pleas for help sewn into Shein clothing by garment workers were widely debunked. But the watchdog group Public Eye, in a November 2021 report on factories that work with Shein, said its researchers interviewed three workers whose hours exceeded national legal maximums, and discovered some workshops with blocked corridors and stairways.

Ms. Taylor hasn’t been swayed. If there were reports the company was violating child labor laws, for example, “I would definitely be against that,” she said. “If the workers are complaining they’re not being paid as much, that’s completely different than saying they’re forcing children to work.”

“How can I stand against them if I don’t have anything to back it up?” she said, suggesting Shein has become a target for being an “underdog.”

Last August, when Ms. Taylor got married, she and her husband decided to plan their wedding on a budget and save for a down payment on a house. After getting an $1,800 quote for a gown from a traditional bridal boutique, Ms. Taylor started searching online for “something simple but very sexy and classy,” she said.

She found a slinky, low-back white gown on sale on the Shein website for $39 Canadian. (Yes, Shein has several wedding dress options. It also has pet hammocks, wigs, toothbrushes, rugs, milk frothers, blister patches, fake toenails, steering wheel covers and a robust selection of lingerie and baby clothes.)

A TikTok video she made about the dress this spring has since been liked more than 900,000 times. Shein reposted it and sent her two $100 gift cards, which she used to place large orders that she later filmed as haul videos. In the future, she may join the infantry of influencers creating paid content for the brand.

Initially, though, Ms. Taylor didn’t tell people the dress came from Shein. It wasn’t that she was embarrassed, but, she said, “I just felt like if I look expensive, I’m not going to tell you I’m cheap. If you see it as valuable, I’m not going to say it’s not valuable.”

She feels similarly about criticism that Shein knocks off big-name designers. She recently bought, on another website, a pair of $29 heels resembling a Balenciaga design. While Ms. Taylor supports “originality, 100 percent” — and said she’s against logos being used on fakes — “I do think that people deserve to have nice things and not pay that kind of money. A lot of us that work regular 9-to-5 jobs can’t afford $2,000 shoes.”

Steven Prugar, a 32-year-old information technology professional in Pittsburgh who uses the pronouns they and them, said that Shein’s prices and wide variety of plus-size options have allowed them to experiment with their personal style — to learn what works for their body type — after coming out as nonbinary in 2020.

“You can build out an impressive wardrobe without breaking the bank, which is really nice, especially for a lot of people who are medium- and lower-income that can’t afford to spend $100 on dresses,” said Mx. Prugar, who estimated that about one-third of their wardrobe is Shein. .

Over the years, they’ve also noticed an uptick in Shein’s quality along with its prices; dresses that were once $10 may now be $20, but the fabric can withstand more washes. Lately they’ve been averaging one or two orders a month — typically about eight items for $100.

About a year ago, Mx. Prugar began using online groups as fashion sounding boards, getting feedback on outfits and sharing product recommendations.

In one Facebook group, people post Shein looks worn to birthday dinners or divorce hearings, on vacations and at musical festivals, for themed boudoir shoots or for their children’s first days of school. They share screenshots of their staggering orders: a first-time shopper who paid $796 for 79 items; another who spent more than $2,800 on Shein over six months, with payments split up on Afterpay.

But even among these brand enthusiasts, conversations about Shein’s environmental impact or lead levels occasionally emerge. “I get it,” Mx. Prugar said. “But when you dig down in any product or service, there’s going to be ethical problems somewhere during the supply chain.”

While Mx. Prugar has been willing to boycott companies like Chick-fil-A for ethical reasons — concerned about its past donations to anti-L.G.B.T.Q. groups — Mx. Prugar generally feels that “every company you buy from has a lot of skeletons. There’s really not much you can honestly do about it.”

That isn’t going to stop Shein from trying. In September, the company plans to start a social media campaign to give people an “inside look” at the company’s efforts around labor, sustainability and product safety, said George Chiao, the U.S. president for Shein. It has also put more effort into “driving home the idea of accessibility — that Shein is an accessible brand.”

“While most of these allegations, rumors and attacks online are false, we are partly responsible for the spread or perpetuation of these false narratives,” said Mr. Chiao, who has been with the company since 2015. “We’ve neglected really communicating and engaging more with our customers and our community.”

Still, Mr. Chiao believes much of the negative online discussion about Shein is a result of people falling “prey to peer pressure,” he said, comparing the online debates about Shein to the kind that unfold in politics.

He knows that most of the customer base remains unmoved, still fixated on the low prices.

“I don’t even go to H&M anymore,” said Mr. Jaime-Vega, one half of the Dallas couple who got engaged at Shein, referring to the higher prices. Ms. Alvarado gestured at her large bag: a $100-or-so mishmash of shoes, clothes, accessories and beauty products.

“I definitely wouldn’t be able to buy this much stuff at H&M.”