Godot 3.4.x
- In the Project Export window for Android, scroll down to Permissions section
- Change the size to 1 (or increase the size from the existing value) for "Custom Permissions"
- Add "com.google.android.gms.permission.AD_ID" (without the quotes) in the value field
Also on the Play Store you need to update the "App Content" settings for "Advertising ID". Ensure that you enable "Analytics" and "Advertising or marketing"