> I received my 1st Pfizer vaccine in June and around 3 weeks after the vaccine I started experiencing frequent irregular heartbeats. Sometimes it was every day, then sometimes once or twice a week. I still experience ectopic heartbeat now (although much less frequently) as a result of the vaccine 6 months later.

Way before Covid I had a panic attack which led me to believe that my heart was not working properly. I got everything checked and it was all good but in the following months I regularly noticed irregularities which have since subsided. I'm almost sure that this was not due to any actual change but the main reason was that I was simply observing my heartbeat much more closely, feeling my heart racing etc. which was in turn actually making my heartbeat more irregular.

Of course your problem might be more physiological but I just want to point out that mind and body are closely connected and it's very difficult to observe such an effect and pinpoint it to a certain event (for example the vaccination).