This KB is a hotfix for defender Platform. not defender antivirus signature.
This KB firstly delivered to users in 2023.3.
but lately in middle of 2023 it was postponed because more BUG was found in this hotfix. (Local Security authority protection is off. Your device may be vulnerable)
maybe now Microsoft has solved the proble so the KB is again delivered to users.
third-party AV may stop windows update getting defender antivirus signatures but you probably still get updates for defender program itself.
these are more likely to be ad pop up by adware or your broswer. I mean virus infection scam.
I do not think you actually have MacAfee software on your PC.
try restore your broswer settings, uninstall all unnecessary software.
if the adware is deepply inside, you can try some third-party solution such as malwarebyte.
try:
Open the command line as administrator.
Enter the commands one by one, pressing Enter after each line:
netsh winsock reset
netsh int ip reset all
netsh winhttp reset proxy
ipconfig /flushdns
Restart your PC.
each K version you had ever installed on your windows, it will leave such a folder
it is ok to delete them because I tried to do so
but be careful, if you accidentally crippled these hidden Partition, your OS will not boot up