I can confirm this is still a major issue. I actually made an account just to post this.
I changed the date to test something on my computer, and it "invalidated" my subscription because it was over during the fake date period. Windows defender sent me a notice going "hey, we're taking over because your subscription needs to be renewed, no problem here!". Ok sure, just a simple restart should fix it. I changed the date back using auto date/time and restarted, now it's stuck having real time protection off. The only thing I can see to do is to reinstall or disable windows defender through the registry, both of which are such massive pains I'm considering looking at other antiviruses since I don't want this to happen every time I have to change the date a year or so ahead.
