You got Covid four times? Did you keep up with boosters? The effects of vaccinations wane after about six months.
The vaccine doesn't necessarily prevent you from catching Covid, although it does lessen the chances of that. It primarily prevents the disease from making you extremely sick, as in needing hospitalization.
My suspicion in your case, since you previously had an enviable immune system apparently, is that Covid itself likely affected your super-power, not likely the vaccine.
Totally sucks, I know.
I didn't catch Covid until just over a year ago. I stayed on top of all my boosters. The acute case I had was quite mild, but, lucky me, developed into LC.
(The best-laid plans of mice and men...)