Before mark it as duplicate please read the question.
I have set both SHA1 and SHA256 in my google console.
I have tried many way but still facing e
A lot can go wrong and I struggled for a very long time to fix this issue. My fix was that I needed to select the support email address in the settings of my firebase project.
Good luck
Johan
you can try to do a flutter clean to rebuild from 0 the project. It works for me.
flutter clean