Over the last couple days, I have noticed a new breed of Mastodon spammer, one that compromises old and unused/abandoned accounts and then adds a spam URL in the profile and starts following users.
I have three examples so far, all of them on mastodon.social (I have reported the accounts to them already):
IronChitlin@mastodon.social
onionfriend@mastodon.social
Adam_@mastodon.social
Notice the join dates, 2017 or 2018 and also the URL format.