Hi there.
Same here on my FP6 since the app was updated to version 9.51.0 yesterday. Fails with the message that “Something went wrong” on the MitID verification step, which is the Danish national digital ID. Using a key generator since the MitID app doesn’t work either. Now looking for a way to downgrade the app, fearing that it will not solve the issue. My guess is that the app is now looking for some Google security components on the phone and fails. This is just too bad.
Update:
I actually managed to solve the issue with the current MobilePay version by using the Microsoft Edge browser. The MitID security step is opening a link via a browser, and the other browsers on my phone all failed this step. So I installed the Edge browser, set it as default browser, rebooted the phone, opened the Edge browser, just jo make sure it was running in the background, and then tried to set up MobilePay again, and this time all steps was accepted. I don’t know if your issue is identical (in Finland?), but it is worth a try mayby? Also this solution would apply to all users in Denmark.