Windows can be configured to automatically sign the user back in after a Windows Update restart. Some protections are in place to help ensure this is done in a secure fashion; however, disabling this will prevent the caching of credentials for this purpose and also ensure the user is aware of the restart
To fix this configure the policy value for Computer Configuration >> Administrative Templates >> Windows Components >> Windows Logon Options >> "Sign-in last interactive user automatically after a system-initiated restart" to "Disabled".
Server 2019: https://www.stigviewer.com/stig/windows_server_2019/2020-06-15/finding/V-93269
Server 2016: https://www.stigviewer.com/stig/microsoft_windows_server_2016/2021-09-29/finding/V-224956