So, way to dodge the question.
What I asked was " in many GPL projects there are numerous copyright holders. Therefore, who is going to be the one to sue over the issues and optional seek damages"
You responded with "they".
That's not addressing my point, which is asking about which actor is taking action, why they are and not another actor, etc.
Like, is someone who contributed 3 lines of code 7 years ago going to be actively suing people?