From what I have heard, they had a private Discord (this one maybe?) for Patreons where people shared pirated ROMs. Furthermore, they allegedly used binaries from Nintendo. In some places, this may not have be an issue. EU for example considers this software (binaries) to be the property of the customer if it is needed for the Switch to work as intended. Furthermore, EU makes exemptions for reverse-engineering for interoperability reasons, which Yuzu and any emulator surely do. I do not know what EU law says about distributing these binaries though. The point that I'm trying to make here is that the developers should have learned German and moved to Europe.

Probably the biggest issue was the piracy. I guess if they had not made piracy a part of their business, things would have turned out differently. I'm not making a moral argument for or against piracy, I'm just stating that it's difficult to make a business around it while being in the spotlight at the same time, as Yuzu was.

As an emulator, it's really a cool project and I hope it lives on and stays maintained somehow. I also think such work deserves to be compensated for.