A potential mechanism for Covid to produce lingering symptoms would be some kind of mast cell activation syndrome. I believe that "long Covid" is probably a mix of that, actual lung or vascular damage that takes time to recover (we have a friend who suffered lung damage and referred to the recovery period as "long Covid"), and some (possibly quite large) amount of psychosomatic subjective experience and amplification of lingering symptoms caused by the relentless hype on this issue.

http://farid.jalali.one/MCAS_COVID.pdf?fbclid=IwAR08nCA9isig...