It looks like there is some configuration mistake. Can you please check once again.
Create a zip file containing both google-services.json(check your app name in it if it is proper or not) and GoogleService-Info.plist. then rename your zip folder google-services. Make sure it only contains both configuration files! and add nit to the Resources tab of the mobile app in Service Studio.
check below properties are correct once:
Name: google-services.zip
Deploy action: deploy to target directory
Target directory: concatenation of firebase. and your app identifier.
Please let me know if it works
Regards,
Swapnil