Stack Overflow's rules for bounties [0] discourage promotional bounties but do not state that bounties cannot be given to the same user or on the basis of the user as opposed to a user's answers.

Stack Overflow failed to enunciate their own rules (or - let's be honest - imagined new rules after the fact), blamed you for breaking non-existent rules, sent you an obviously mostly copy/paste suspension notice (the bit about secondary accounts seems bizarre and non sequitur), and gas-lit you with the imaginary claim that you cannot vote on a post you already voted on which for whatever reason hadn't been logged.

FWIW also a high-rep SO user and had to create a burner account in case there's retribution. We shouldn't have to hide ourselves just to talk sanely.

SO is right to try to protect the bounty system from unintended uses, but not to make rules up on the fly and enforce them heavy-handedly and retrospectively, suspending someone for breaking non-existent rules.

Stack Overflow should make rules for bounties and make them crystal clear and unsuspend you. Can they admit they're wrong - will they do this? Of course not.

[0] https://stackoverflow.com/help/bounty#:~:text=Users%20may%20....