I had the same; had to basically stop doing anything for about two months and hard to do a Masters when you can't focus or do basic math; the fatigue and mental fog was brutal. Walking up the stairs was an issue, and would need to sit down for a break to catch my breath. Just really lucky everyone was supportive.
I went to sick parade and they wanted to do some dimentia testing. Fortunately eventually found a doctor with a bit of common sense who kiboshed that and gave some puffers to help with the massive shortness of breath from basic exertion, and then just monitored that things were slowly getting better. I was a bit of a vegetable though until I got the first vaccine though, and then it started to improve.
Still can't make it through a FORCE test due to exercise related breathing restrictions, and still a bit mentally fuzzy at times, but back to about 60% when I was down to below 10% at it's worst. Really sucks though, as there is no real diagnoses, and having a hard time getting the ongoing symptoms treated.
Great that it hasn't been a big deal for some, for others it was life changing, even though we didn't have a 'severe' case requiring hospitalization.