I was thinking it's only spam servers, but it might actually just be downtime for hetzner or something.
Instances do not get banned on lemmy. You can run any kind of an instance.
That said, part of this could be providers pruning "fake customers", aka spammers, scammers, etc, who "paid" for their servers with stolen CC and SSN.
Edit: Someone up to making an uptime map for Lemmy, placing servers on a map based on where they report originating at? This could help seeing if a specific datacenter has downtime.