It's interesting reading about long Covid (all the best to your wife Steels).
My wife got ill in March 2019 and since then has had a series of problems - ectopic beats, shortness of breath (bending down, climbing stairs, hanging out washing), chest pains, brain fogs, poor concentration and tiredness.
She's had chronic fatigue since 2011 (triggered by stress but kicked in after a virus) which has never gone away.
After spending last year battling for any diagnosis (speculations of glandular fever, costachondritus, silent reflux, some rib displacement thing, menopause) and several trips to A&E worried about palpitations, I can't help to think that long covid is a relative of existing unexplained conditions.
Hopefully some effort might be made to get to the root of these post viral conditions because they are seriously life impacting and it sounds like long Covid is the worst of a bad bunch.