The fight you skipped is the one that never shows up on your record.

Most conflicts are not remembered for who was right. They are remembered for who said the worst thing, and that line gets repeated long after the actual disagreement is forgotten. Walking away from one that was never going anywhere leaves nothing behind for anybody to quote back at you. It looks like nothing happened, because nothing did.

Before stepping in, ask whether winning this would change a single thing. If the honest answer is no, let it pass and accept that a few people will read it as backing down. The clean record you are keeping is mostly with yourself, and it pays out over years.