As someone with long COVID, I can vouch the debilitating mental effects. I was teaching math to 4th through 8th grade students when I got it. I can remember standing in a classroom talking about a lesson and just having my mind go blank in mid sentence. I couldn't function. Not knowing what I was talking about or even where I was. Thankfully the students where very understanding and someone would finish my point I was making. I still suffer from it yet today, nearly 2 years later.
I have respiratory issues despite every CT scan showing nothing more than a couple of small pneumonia scars form long ago. I should be able to breathe just fine with no reduction of lung capacity. It stems from a lack coordination with my diaphragm - It runs backwards when I exert myself causing shortness of breath. Another sign of probable brain injury. And despite using a therapy tool to try and fix the issue, at best it just helps a little.
The upshot is I have pretty much stopped doing a lot of things I used to do because of the difficulties breathing and I spend a lot more time away from people due to an unreasonable fear of COVID.
It has caused me to retire earlier than I wanted to. And my life has greatly changed - and not for the better either.