Windows Server 2019 users must be prompted to authenticate when the system wakes from sleep (plugged in).
A system that does not require authentication when resuming from sleep may provide access to unauthorized users. Authentication must always be required when accessing a system. This setting ensures users are prompted for a password when the system wakes from sleep (plugged in).
Configure the policy value for Computer Configuration >> Administrative Templates >> System >> Power Management >> Sleep Settings >> "Require a password when a computer wakes (plugged in)" to "Enabled".