They hid away in this one paper confirmations of basically all the worst case scenarios;
Immune imprinting, breadth of variant recognition, and germinal center response in human SARS-CoV-2 infection and vaccination
>https://pubmed.ncbi.nlm.nih.gov/35148837/
Spike protein littered throughout the body causing seemingly random side effects;
>At least some portion of spike antigen generated after administration of BNT162b2 becomes distributed into the blood. We detected spike antigen in 96% of vaccinees in plasma collected 1–2 days after the prime injection, with antigen levels reaching as high as 174 pg/mL.
This is why the "vaccines" don't cause a traceable "side effect." Whatever random tissue a person is unfortunate enough to have exogenous mRNA exposed to it will be attacked. Myocarditis for some, nervous system disorders for others, digestive problems for others, etc. The "vaccines" are code which instruct cells to tell the body they have been infected with SARS-CoV-2, so the immune system attacks those cells. When the cells are destroyed, they spill their contents of spike into tissue / blood.
The spike protein in the blood is then attacked by antibodies causing all the clotting problems;
>A practical finding in our study is that the detection of spike antigen in plasma samples is impeded after second dose BNT162b2 vaccination, likely due to the formation of circulating immune complexes of anti-spike antibodies and spike protein, masking the antigen epitopes of the capture and detection antibodies that form the basis of antigen detection assays...
They are saying that antibody levels tank after the second dose, because you already have antibodies from the first, so they immediately start attacking the new influx of produced spike from the second dose. They form what the paper calls "immune complexes." Immune complexes, or antibody / antigen complexes, or agglutinations, induce clot formation and the Compliment System, doing more damage.
So back to the problem of the mRNA vaccines being rolled out to humans without proper trials. The expectation was that the above process would take place in the area of the deltoid and that spike proteins would prime the immune system, and then once the mRNA that was injected was cleared the cells would go back to their normal function, the Major Histocompatibility Complex would start displaying regular proteins again, and no spike protein would be left in the persons body. Obviously as cells die some spike protein would be spilled into tissue and make its way into circulation, but that was expected to be an inconsequential amount, to be cleared by normal function of the immune system quickly, and was stated that the spike protein itself was not cytotoxic. Those three assumptions have proven false, which is where the vaccine side effects are coming from.
Instead of remaining in the injected area and being cleared relatively quickly once priming the immune system the spike protein is showing up all over the body in high amounts. It's been found to cross the blood brain barrier and make its way to the heart (causing the myocarditis that's so prevalent they can't hide it.) The spike protein itself has been found to be cytotoxic, doing direct damage to tissue, and is causing damaging immune responses to healthy tissue that the spike protein finds it's way into. Instead of being a short lived production run that primes the immune system, the mRNA vaccine appears to be littering the body with it and causing wide spread auto-immunity to all sorts of tissue.
TLDR; then you don't get to understand the mechanism behind the vaccine dangers.