The only thing that works right now, Jan 2021, is a version of this. I tried all suggestions here prior to today and tried this, this, this. To permanently disable Microsoft Defender:
Computer Configuration > Administrative Templates > Windows Components > Microsoft Defender Antivirus > Real-time Protection.Open Local Group Policy Editor (type gpedit.msc in the search box).To permanently disable real-time protection: Virus & threat protection > Virus & threat protection settings > Manage settings.Open Windows Security (type Windows Security in the search box).
Tamper Protection must be disabled before changing Group Policy settings, otherwise these are ignored. In newer versions of Windows, Tamper Protection was added.
In newer versions of Windows, Group Policy settings for Microsoft Defender are reverted back.
