I fixed problem,
First of all you must create cloud oauth. I created web application
after that, this web’s client ID and client secret copied to firebase
Steps:
1 - Go to Play Console
2- Select your game project
3- on the “Grow” tab Select → Play Games Services-> Setup and Management → Configuration
4- Click "Add Credential
5-Select type as Game Server
6-Select your oauth Client save
7- on the right top of screen there will be publish button. Click and approve settings.
This will fix leaderboards / achievements system.
Thank you.