same issue. I went through diagnostics and restore points. I was unable to refresh windows and installation disk didn't allow for reinstall - it just asked for product code. I was also having problems downloading from microsoft store. I suspected borked installation.
I have ssd for OS and second old spinning drive with original win 10 install.
I booted into the old spinning drive and cloned it back to the SSD. (back from when I didn't get error). Upon rebooting the SSD OS drive I get the same "your device is missing important security and quality fixes."
I have all important updates. I have not installed feature update 21H1.
I think its a microsoft glitch.