If you are still running Tautulli, make sure that the web interface is not accessible from the internet.
It also appears that you are using (or have used once) a ton of 3rd-party apps & tools. Any of them could leak your token in the case of a bug or security breach.
If you used one of these tools, but don’t anymore, revoke their access tokens here https://app.plex.tv/desktop#!/settings/devices/all
and make sure they don’t run anymore.
(careful to not revoke the tokens of you server, or you’ll have to restore your access with some effort)