they probably need to sue to enforce this, I think this is actually going to be a larger issue than just corgi. copyright with these models really is just a mess

Just consider all model output AGPL. ;-)

What I don't understand is that if a lawsuit happens, then must the plaintiff produce their source code for verification ? Even so a git tree is trivial to change into some other arbitrary code even if a license violation has occurred. I also heard if proven the consequences are that they would lose all revenue starting from when the violation has occured