I was unable to block more gold spammers because “You cannot block more than 100 players”.
So I started deleting old spammers from the block list. However, some of them cannot be deleted. Clicking the x button on their names gives me the message “This player is already your friend, or the request cannot be made.” So these spammers (presumably deleted or banned by now) are just permanently stuck in my block list, taking up limited space. (Why is the block list so limited anyway when there’s so many more than 100 spammers? But that’s another topic.)