Yes, absolutely, and that's the part that bugs me most but I've found that I can work around most of it. For instance, I'm a touch typist and used to be able to type nearly flawless, but now I have to proofread even the smallest communications because there typically will be a couple of obvious errors in it. Highly frustrating. Short term memory issues can be dealt with though note taking.
Now, who is to say that the two are related, this is obviously anecdotal and the one might have easily happened without the other, I had some pretty bad O2 dips though and before everything was fine. So for me the correlation is strong enough to believe there is a connection. But the physical aspect is so strong that for me that is 1:1 related for sure. The mental part is not such an easy to point out difference, it is far more subtle.
Fogginess is an excellent description by the way, that's exactly it.
I'm a bit relieved that it's not just me and that you've described nearly to a T some of the more annoying ongoing things - missing glaring errors and omissions in emails/text (or just leaving completely unfinished sentences that I started and told myself "I'll get back to this one after the next bit") is painful and I've also found that I've kept a LOT of notes and manage a lot of my time through bullet-pointed TODO lists.
You're right that this is anecdotal and as the saying goes the plural of anecdote is not data ... but in my case the change was pretty stark - I was ok, then I was ill, then I recovered and was no longer ill but I felt like my brain was half-asleep most of the time. It sounds like you were the same.
One possible thing is that I've in the past felt a bit mentally dull during times where I haven't done much intensive physical activity. And obviously with gyms being closed and amateur sport cancelled I've only really been able to go for hikes which isn't quite the same. So my one remaining hope is that things snap back into place a bit once this is over - but who knows.
In any case I hope for both our sakes we can figure out what's going on and how it can be alleviated (if not fixed entirely)
I'm using an old racing bike on a stand to keep in shape, that really helps.
edit: Case in point, and I only noticed it now, my previous comment reads 'though' when I meant to write 'through'. That's the sort of thing that happens much too frequently now.
Now, who is to say that the two are related, this is obviously anecdotal and the one might have easily happened without the other, I had some pretty bad O2 dips though and before everything was fine. So for me the correlation is strong enough to believe there is a connection. But the physical aspect is so strong that for me that is 1:1 related for sure. The mental part is not such an easy to point out difference, it is far more subtle.
Fogginess is an excellent description by the way, that's exactly it.