Just to add some nuance, a server can block other servers. If one server does something that breaks another's rules, the other may block.
Extreme example: years ago a prominent neo-nazi server tried to join Fediverse, almost all other server owners blocked it. Neo-nazi server ended up so isolated, it gave up and left.
In less extreme cases, servers may be blocked by some but not others. There are also degrees of blocking.
Server about pages have info about their blocks.