Hmm...

Ok I checked the pricing page and funnel is available in the free tier (limited to 3 users) but not the $6/user/month tier - which you need for more than 6 users... strange pricing structure but I guess I see the logic.

Any chance you were asked to upgrade from $6/user/month to $18/user/month and not free to $18/user/month?

https://tailscale.com/pricing#application-networking

Yes, we were on the starter $6 plan. The feature we got messaged about was SSH management, iirc.