This is great, you should remove all signature because the spam is too much.
Those signatures that you are seeing are mostly because of signature campaigns. They are not spam if the users that you are seeing wearing it are different. I don't see signatures as spam. All of the signature campaigns are crypto related, it's normal for a forum to have such. There's a thing a about signature spamming, correct me guys if I'm wrong, but I do think you can report a user to the campaign manager if he is spamming his signature. I don't know if it is necessary since the campaign manager can just disregard those posts and not count them, or warn the user or remove him from the campaign.