So introductions to KYC in a bounty means the bounty manager is a scammer? There are few moves like this from some old bounties and it's the project team fault not the bounty manager, if the team decide to change rules there is nothing that the bounty manager can do about it, if you don't want to work for nothing you will have to comply
As said by the OP the KYC is decided by the team and not the bounty managers . It's on the users to decide if they want to participate in bounty if it's needing Kyc. Also the project should be clear about the Kyc requirements from the beginning.
In fact, that if the KYC implementation will always be decided by the team at the end of the campaign. I can only mention some bounty that's fair to mention the KYC verification when it was getting started like radix.
So many bounties have decided this at the end of the campaign. The bounty manager must also ask this since it was getting started or try to make sure if there will be a high chance for the KYC to be implemented to the participants or it will become mandatory for the participants to complete the verification.