On LTSC 21H2, services.msc shows it Auto-start delayed, but stopped. I generally have Defender disabled and don't know implications (not aware if/when that service runs), but I haven't noticed any issues with general desktop use after KB5049981.
borncity.com/blog/2025/01/15/windows-10-server-2022-dienst-sgrmbroker-startet-nach-jan-2025-update-kb5049981-nicht-mehr/#comment-205812 borncity.com/win/2025/01/21/windows-10-server-2022-microsoft-confirms-sgrmbroker-issues-after-jan-2025-update/
The issue is limited to 22H2. Did not test on LTSC 2021. I confirmed LTSC 2019 is not impacted. My advice is to only apply the workaround above if required. My two cents.
Thank you. So one can conclude the System Guard Runtime Monitor Broker Service is not part of Windows Defender on LTSC 2021 and 22H2 as Microsoft said this service was originally created for Microsoft Defender, but it has not been a part of its operation for a very long time. Workaround and that's it. On LTSC 2019 there are no issues, so the service should remain enabled. My two cents.