someone who will strike down anything and everything they deem is infringing on their copyright, even if the violation is very minor or can be rebuked. if the attempt fails, most commonly they will then sue the violator. they also might have ulterior motives.
someone : *uses a photo that's in the public domain in whatever*
someone else (copyright snowflake) : YOU CANT USE THAT
someone : uh, I bought this photo off a stock image website
copyright snowflake : I'm not talking about that, I'm talking about that formatting/editing style you're using, thats mine!
someone : its only like 2 seconds ffs, I can just change it or cut it out.
copyright snowflake : sorry! I have to send a strike!