custom domain
From what I gather, this refers to the email address you sign up with.
If you use something like a non-gmail email address when signing up, it starts you off on the business plan with a trial (which you can instantly change to free). (Note: they’re gonna change this auto-detection thing with shared domains soon due to a security hole.)
I believe you can still use a custom domain (instead of the randomised *.ts.net provided one) with DNS lookups in your tailnet, on the personal (free) plan.
WTF! How did it hit target already? Hope there wasn’t any bot farming involved…
Otherwise, pleasantly surprised!