Unity Ads keeps players from signing in Google Play Services

Hi !

I recently created a test app for android, everything has been setup right and by that i mean i can publish my game and everyone can download it.
All the process about SHA fingerprint are done.
I even configured Firebase in my game and everything works A1
BUT Whenever i try to add the Unity Ads services, all of a sudden, we can't sign in Google Play Services AT ALL.

Like the manifest is being modified or something.

The log cat throws me this error :



And the second i remove Unity Ads Service from my game, everything works fine and i can sign in and play.

Thanks in advance !