Oh cool - if you go to report an account on Mastodon and tick every recent post it's made, you get the option to report the account to every server with someone it @'d in those posts.

This means not only does the report go to the server it's from, but also other admins on servers targeted by their bullshit, so even if the host server is slow to shitcan the account, several other admins have a shot at reducing the harm to their local users while you wait for the actual host to do something.