Atlassian is currently rolling out new sharedSecrets for each app & instance in an effort to move away from single sharedSecret to per-app / per-tenant shared secrets. You will probably have received new installed lifecycle events. It is absolutely paramount that your app is capable of receiving these updated sharedSecrets, i.e. that your code supports updated client information whenever a lifecycle event occurs. Could it be that you are currently not handling these updates in your app?
See also: