You can check for inactive accounts you may be following with this:
https://yeghro.site/nostr-inactive-users-checker/
and unfollow them if you like.
Discussion
very useful tool to help prune your following list if you're getting close to that 1k following count where things start getting weird
nostr:note15pwpj72utm3pd28cy0dsl0j4asqkey5ysmvds7lc8rz8ztrp8hws3ja2mz