As of about a month ago, you can also sign up to Tailscale with any OIDC-compatible identity provider, so if you don't want to use Gmail or Microsoft you can self-host your own!

https://tailscale.com/blog/custom-oidc/

Seriously, if you use one of their recommended identity providers and their "AI" bans you, can you change your access controls on tailscale to another provider? Ideally without physical access to the other machines.

The list of identity providers is just ginormous companies that are likely to automatically ban accounts.