Meanwhile, several companies are no longer offering bounties. It's becoming tedious to sift through all the AI-generated submissions, many of which are false positives.
Don't worry, the fact that you may be able to get something worth a dime out of these models if you really try does not yet mean you won't get flooded by slop from people who did not bother at all. The background noise is elevating rapidly and discerning signal from it takes more and more effort.
Just require people submitting a bounty to post an evaluation fee. If it's a real bug they get a refund and the bounty. If it's AI slop, you keep the evaluation fee.
You don't have to determine if it's an AI or not. If AI finds a real bug then it can get the bounty. If a human pays to make you read artisanal hand-crafted word salad then they don't get a refund. Real bugs get the bounty, imaginary bugs pay the fee.
This might work but only if the evaluations are done through a trusted third party entity where none of the money ever reaches the company you're submitting to.
You only need things like that for non-iterated games. A company that gets a reputation for keeping the money when it's a real bug would stop getting real bug reports.