Why does the program work when installed on a device directly, but does not work when installed from Google Play?

Question

Android

There is a project created in Unity for Android.
If I install it from Unity directly on the device, then everything works fine, authorization in Goodle Play passes, the database works.
If I install the same project without any edits through the Play Market, then the program does not work: authorization in Goodle Play fails (gives Canceled), the database does not work (gives connection failure).
At the same time, the program worked before, and everything was fine through the Play Market too.
The problem began to arise after experiments with connecting statistics from Firebase, which somehow worked strangely: the Firebase code tightly hung Unity, but worked on the device. I could not get the other code options given in their examples to work.
In one of the versions, I also stuffed an authorization check on Google Play into the Update method. After that, this version worked, but the next one doesn't. I have thoughts that Google banned authorization due to frequent requests (I don’t know if this is possible), but then why isn’t the database also working?
I removed all the Firebase code, but it still doesn't work.
Tell me, in which direction to dig?

Answer 1

Play Market - then the program does not work: authorization in Goodle Play does not pass (issues Canceled

Wrong fingerprint used for verification. When you upload it to Google Play, it is re-signed, and accordingly the hashes and that's all at the key change.