Anecdotally, this strongly mirrors my personal experience with long covid symptoms. I’m relatively young (32) but have noticed I don’t recover well in result to neurological injuries: loud noises which didn’t damage my hearing but left me with tinnitus, and a very mild concussion which has now taken the greater part of a year to stop feeling dizzy from.
So, the more spike protein, the worse the symptoms, but also vaccination with Pfizer/BioNTech reduced the number of spike proteins stuck in the marrow. I wonder why mRNA making more spike proteins improves the situation