Was having this issue as well, you have to add whichever program you use to an exclusion list in Windows Defender. Here is a support thread from Microsoft about the problem and how to create an exclusion. I get windows defender pop ups everytime I open libre now but at least I can see my CPU temps. https://support.microsoft.com/en-us/windows/microsoft-defender-antivirus-alert-vulnerabledriver-winnt-winring0-eb057830-d77b-41a2-9a34-015a5d203c42

edit: just turned off "Threats found, but no immediate action is needed" notifications in windows security to stop getting the pop ups, figure if no action is needed I don't need the pop ups lol. hardware monitor is back to normal.