This is an informative website on Dsyautonomia:
thedysautonomiaproject.org/...
Dysautonomia (dis-auto-NO-mia) is a term used to describe any disorder of the autonomic nervous system (ANS). This article covers a broad range of topics including symptoms, types of dysautonomias, who is affected, and treatments.
I have also found this video with relates to long covid too, which is really informative (currently listening to):