APNs returning 410 unregistered token

We encountered an issue where some users were unable to receive push during the overwrite installation process。 After a while it was normal again。 Checking the code shows that the registerForRemoteNotifications method is requested twice in a short period of time。 Therefore, we want to know what are the possible reasons for 410 unregistered。 Thanks。

APNs returning 410 unregistered token
 
 
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