That a fake popup if it's telling you there's malware on your PC, since unless McAfee itself was truly installed, it can't be the source of what's being displayed.
Thit means the only true question is wat's displaying the fake popup message.
First, I see you previously must have tagged another thread regarding Google Chrome notifications for McAfee as helpful, so if that didn't actually solve your problem, have you truly determined these types of browser displayed notifications aren't involved in your issues? I ask because these are common way these popups are displayed without being detected as malware, since they're not, they're simply Windows notifications displayed by a web page that you allowed sometime in the past.
If you're not sure, look for either the Google Chrome or Microsoft Edge browser title near the top of the popup, since if that's present, it's highly likely they're a browser notification that can be easily turned off if you just tell us which one is involved.
If not, then it's possible the popup is being displayed by malware/adware, but I'll wait for your response before going further into how to try and remove those.
Feel free to attach a screenshot image of the popup using the Windows Snip & Sketch tool to capture in your next post if you want aid in identifying the possible source of the popup.
Rob