Just lock the thread till u have better reason to open it
OP probably is right, just based on how prevalent bounty cheating is....but OP, heed the words written above. You have nowhere near enough evidence for anyone to act on at this point. If you can link accounts via blockchain transactions and they're enrolled in the same bounty/bounties, then you might have a case.
Until then, just lock this thread or else it'll become a shitpost haven. Props to you for looking for this stuff, but there has to be sufficient proof before anybody gets tagged.