This report was intriguing for explaining the cause of the brain-fog and similar Long-Covid symptoms...

Title: Peptide from SARS-CoV-2 spike protein forms amyloids
"In lab tests, immune cell enzyme cleaves spike protein to yield fibril-forming peptide. (by Celia Henry Arnaud - May 31, 2022) Spike192, a peptide from the SARS-CoV-2 spike protein, forms well-defined amyloid fibrils. Researchers have also speculated that regions of the protein can clump up to form amyloid fibrils like those seen in diseases like Alzheimer’s"....(The researchers...) "could use the spike peptides to induce amyloids in fibrinogen, the protein that forms blood clots to control bleeding. "

[cen.acs.org].