This is first time me releasing app so I'm facing this issue
Your Android App Bundle is signed with the wrong key.
This app was already released for internal testing for old version by some other developer. He didn't wrote keystore password and keyStore alias in gradle.properties file. I don't know how he did it but I don't have any access to it. Is there any way I could create new keystore and upload it? There is a debug.keystore file availble in android/app folder.