I am using Unity 2020.3.16f1 and Cloudoncev2.7.3 and The problem is that my app connects to google play services because I see that in google cloud someone connects to the google play services but in the app there is no sign of any connection only black screen pops up for a second and after that I can’t access any leaderboards and achievements.
Google play services don't pop up normally I just see a black screen for a sec and then can't open l
Get out your adb logcat
and see if there are any exceptions being thrown related to this.