@liaizon what is known are the domains used...
https://github.com/greyhat-academy/lists.d/blob/469f6cc11c2d22b3b26ab3806ff2e4aa3d5ebaec/activitypub.domains.block.list.tsv#L42

Feel free to denylist them yourself, too by pulling this blocklist:
https://raw.githubusercontent.com/greyhat-academy/lists.d/main/activitypub.domains.block.list.tsv