PLEASE if you run or used to run a fedi instance, and that instance shut down and it was running on an shared VPS

PLEASE PLEASE PLEASE remove the DNS records for the old domain (and pref. keep the domain renewed)

when you release a VPS the IP still gets allocated to someone else eventually, and if that still points to your domain a lot of nasty stuff can happen including cert hijacking and fedi impersonation.

if you ever run a fedi instance, you essentially can never let go of the domain, and you must ensure it's clean, otherwise the instance can potentially become fedi malware and there definitely are vulnerabilities in how AP is implemented (we just don't know how yet.)