Bad Authentication - while receiving push notifications

Question

I developed a GCM service to receive push notifications on my app, it was working perfectly the last year till today, beginning from today I'm Not receiving any push notification on any device and instead I'm getting the following error log:

[GoogleAccountDataServiceImpl] getToken() -> BAD_AUTHENTICATION. Account: <ELLIDED:332570614>, App: com.google.android.gms, Service: oauth2:https://www.googleapis.com/auth/games
fbl: Long live credential not available.
    at fbm.b(:com.google.android.gms@11951440:10)
    at fbm.a(:com.google.android.gms@11951440:50)
    at ezw.a(:com.google.android.gms@11951440:37)
    at gnu.a(:com.google.android.gms@11951440:7)
    at gnu.a(:com.google.android.gms@11951440:155)
    at gmu.a(:com.google.android.gms@11951440:2)
    at gms.a(:com.google.android.gms@11951440:17)
    at gms.a(:com.google.android.gms@11951440:6)
    at cob.a(:com.google.android.gms@11951440:25)
    at cob.a(:com.google.android.gms@11951440:80)
    at ewz.a(:com.google.android.gms@11951440:6)
    at ewy.a(:com.google.android.gms@11951440:2)
    at ewy.e(:com.google.android.gms@11951440:6)
    at ewx.a(:com.google.android.gms@11951440:1)
    at eyn.getAuthToken(:com.google.android.gms@11951440:7)
    at android.accounts.AbstractAccountAuthenticator$Transport.getAuthToken(AbstractAccountAuthenticator.java:244)
    at android.accounts.IAccountAuthenticator$Stub.onTransact(IAccountAuthenticator.java:113)
    at android.os.Binder.transact(Binder.java:507)
    at cqi.onTransact(:com.google.android.gms@11951440:3)
    at android.os.Binder.execTransact(Binder.java:573)

W/Auth: [GetToken] GetToken failed with status code: BadAuthentication
D/CompatibilityInfo: mCompatibilityFlags - 0
D/CompatibilityInfo: applicationDensity - 420
D/CompatibilityInfo: applicationScale - 1.0
W/Auth: [GoogleAuthUtil] GoogleAuthUtil
 W/GLSActivity: exl: BadAuthentication
                   at ewz.a(:com.google.android.gms@11951440:13)
                   at ewy.a(:com.google.android.gms@11951440:2)
                   at ewy.e(:com.google.android.gms@11951440:6)
                   at ewx.a(:com.google.android.gms@11951440:1)
                   at eyn.getAuthToken(:com.google.android.gms@11951440:7)
                   at android.accounts.AbstractAccountAuthenticator$Transport.getAuthToken(AbstractAccountAuthenticator.java:244)
                   at android.accounts.IAccountAuthenticator$Stub.onTransact(IAccountAuthenticator.java:113)
                   at android.os.Binder.transact(Binder.java:507)
                   at cqi.onTransact(:com.google.android.gms@11951440:3)
                   at android.os.Binder.execTransact(Binder.java:573)

I'm receiving this log with every push notification message sent to the app.

I came across similar issues like here and here but they couldn't help in finding a solution for me.

My main problem is that I don't know how to even track that issue, and is there is any server related issues that can cause that or not. I need precisely to capture the scope of what I'm facing.

p.s. it's not working also on emulator.