okay I was in the BETA. v3.10.0 does not have this issue.

I have this problem right now.
Got a new phone as the previous one got destroyed in an accident.
So setting everything up on the brand new never-used phone, and when setting up Steam, I just downloaded it from the app store. (Read: Brand new phone. Never used before. Ever. Sealed package out of the store. Fresh from the factory)

The very first thing the Steam app asks for is "Enter family PIN code".
I have never used family mode... ever. Never set it up. Has never been used on my account. Ever. I don't have any use for it.

I don't even get an alternative to log in to my account, or enter the restore serial which I have saved on a secure note elsewhere.

Why do I even have the backup/restore serial if I cannot use it when fresh-installing steam mobile app on a brand new never-used-before android phone?

The solution: log in on a web browser on another computer. tell it I don't have the authenticator app any more. Jump through all the hoops and MFA steps to regain the account without the mobile app authenticator. Once done, I was able to get the mobile app to show me a login prompt instead of family pin code. It somehow detected my google play store account and sensed there is a "lockdown", so it refuses to let me log back in or restore from a backup.

The "enter family pin code" blocks all other menus making it impossible to do anything else. Resetting the app did not help.

Lesson learned: Do not use the authenticator part of the mobile app. It just refuse to let you restore it on a new android phone.

Yeah

ci