Probably just someone trying to do a copyright claim on you for no reason or to hold your content hostage. I heard this happens casually to some content creators to force them to pay a minor fine to someone who copyright claimed them so they'd withdraw the claim.

Youtube automates this sometimes that's why if someone tries to copyright claim you, it auto flags your video temporarily. Best open a support ticket of the sorts with youtube and see if they can force the guy to withdraw the baseless claim.