The accusations against eXch have nothing to do with fungibility. Cash is also fungible, yet it is possible for it to be laundered. People are simply in denial, like they were with mixers, because they don't want to lose out on their weekly payouts.
The FBI has put out a statement in which they allude to eXch, mentioning how a portion of the stolen assets were converted to bitcoin.
https://www.ic3.gov/PSA/2025/PSA250226Bybit has created a new website where eXch is the only service listed in the Bad Actors category. According to this website, nearly $100 million from this hack has been laundered through eXch.
https://www.lazarusbounty.com/en/detail?entity=eXch