I had a similar issue with my Pixel 6 Pro on a Beta and after a couple of months or so it just started working. I opted to move everything to Pixel Pass but it wasn’t registering that I had it even after following the instructions from Support to terminate the previous standalone subscription. I never “officially” got a report after filing a bug report that it was fixed (could have been a notification I didn’t enable but who knows) but a review of the changelog showed it was done. I am assuming that you are using the free Google One VPN that was rolled out with the below instructions or had a previous standalone 2TB subscription.
If you did not move from standalone Google One to Pixel Pass, try these steps:
Go to App Info and Force Stop
Clear Cache and Data
Reboot phone
Once booted and fully settled, launch the Google One app and log in if prompted to connect your Google account
Test the VPN
If you did switch like I did or still have issues after trying the above, DEFINITELY submit a bug report via the feedback app. The above may work if you did switch but you’d have to try it to see. It was successful before when I had a similar issue prior to moving to Pixel Pass with my Pixel 4XL with a paid 2TB sub. It should work too even with the free version offered on the Pixel 7 line.
I noticed this the other day as well. Contacted Google support and they had me uninstall and reinstall the Google One app. Seems to work again after I do that, but it’s annoying to have to do that every time I want to use it.
I have two Google accounts on my phone. I have had some success by opening Google One, switching to my secondary account, trying to activate the VPN (which fails) then switch back to my primary account and activate the VPN. This has worked twice for me so far.