How long did you recover the deleted account? As usual, it may need some time to recover it.
Besides, please check if there are any retention policies in place that may be causing the user account to be deleted automatically. If so, you may need to adjust these policies to prevent future deletions.
Second, check if there are any audit logs or activity reports that may shed light on what happened to the user account. This may help you determine if the account was deleted manually or automatically.
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