One of the best things to do to not get rekt by these kinds of bounty campaigns is checking first their Terms Of Services, especially in their bounty campaign, you should check if there is term that they are allowed to change the mode of payment for their bounty campaign or changing smart contract beside from escrowed token is allowed. Because if so, you can't accuse them for scam project.
Speaking of in USDT rewards for bounty campaigns, it's really difficult to find bounty campaigns that are offering some stable coins as mode of payment.