Rarely in Olympic history had a single company been as ubiquitous as LVMH Moët Hennessy Louis Vuitton, the luxury goods empire owned by France’s richest family.

As the Paris Olympics’ biggest corporate sponsor, LVMH was everywhere. Its Moët & Chandon champagne flowed in V.I.P. suites. French athletes were clothed by LVMH’s Berluti fashion house. And, in contravention of at least the spirit of the Olympic charter, Louis Vuitton luggage was trotted out during the opening ceremony and seen by more than one billion people worldwide.

But its most significant role involved the Olympic medals, which were designed by Chaumet, a luxury jewelry and watch maker and part of the LVMH group. Gold, silver and bronze — the very best athletes would take them back home as mementos of their feats at the Paris Games.

Now those medals are falling apart — and LVMH has fallen silent.

In just over 100 days since the Olympics closed, more than 100 athletes have asked for their crumbling medals to be replaced. Last month, Clement Secchi and Yohann Ndoye-Brouard, French swimmers, showed their flaking medals on social media. “Crocodile skin,” Mr. Secchi wrote. And just weeks after the Games ended, Nick Itkin, a U.S. Olympic foil fencer, posted a video on Instagram of his bronze medal losing its shine.

Medals have had to be replaced in other Olympics — notably in Rio de Janeiro in 2016. But in no previous Olympics has a company stamped its brand credentials so prominently.