Dumdum If you run your own instance, then nothing to worry about.
2FA is also recommended, but do the instances you don't manage really have access to your passwords ? They're supposed to be hashed.
An administrator of an instance can access the messages of users who use his instance, read them, modify them and delete them, just as a forum moderator can, but that's very different from being able to access users' passwords, I've never read anything that confirms this.