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.
What announcement? There’s been a new Personal Plus plan around for several months already - introduced without much fanfare, and simply brings the user count from 3 to 6 for a fixed small fee. Presumably this is due to feedback from personal users wanting to contribute something other than nothing.
Where do you see the free Personal plan has changed at all?