https://wccftech.com/microsoft-resolves-windows-10-20h2-mmc-issue/

Latest Windows 10 October 2020 Update was a comparatively stable feature update, but some bugs were still there to be addressed. The Windows maker has today tagged the last officially acknowledged bug in version 20H2 as resolved.

After updating to Windows 10, version 20H2, you might receive the error in LSASS.exe with the text "Your PC will automatically restart in one minute" when interacting with any dialog window that lists users, for example accessing the sign-in options settings app page or the users folder in the Local user and groups MMC snap-in. This issue only affects devices in which any of the local built-in accounts have been renamed, such as Administrator or Guest. You might also receive an error in the Application Event log with Event ID 1015 that LSASS.EXE failed with status code C0000374. C0000374 is related to heap corruption.