Brain fog was a common symptom in our society far before Covid.
(I did experience “brain fog” simultaneous with my flu-like symptoms, but couldn’t really tell you if that lack of focus was actually a symptom in and of itself or it was just a consequence of feeling like shit because of all the other symptoms. I know it’s a very common thing people bring up, but it also doesn’t surprise me that having a big ol’ headache, sinus congestion, a crappy cough, a super sore throat, and full body aches and chills would also result in not being at your cognitive best. I’m not sure if that’s called “brain fog” or just “part of being real sick.” But yeah, I did have it.)