If you're on a Mastodon server that needs to have the highest level of user safety, you might want to talk to your admin about whether they should activate "limited federation mode".
This mode prioritises safety over connectivity, and means a server manually chooses which servers it allows federation with, while blocking all the rest by default. More info at:
➡️ https://fedi.tips/creating-an-isolated-server
(Its main disadvantage is it's a lot harder to follow accounts on other servers.)