The only reaction I had to my Pfizer shots was a few hours of soreness at the injection site, both times.
I'm wondering some of us who saw few or no symptoms after the shot are people who had already been exposed to Covid, and who had successfully built up immunity from that exposure without seeing any major symptoms.
For myself, I mysteriously developed a persistent cough in mid-December, which did not stop until late March. That type of problem is not normal for me, and the fact that it persisted for 3 months is also not normal for me.
There is credible evidence that Covid was in the US by December, so its possible this is what happened for me, and it would explain why the shots didn't cause any reaction.