I've also been having heart problems. We (DH & I) had covid last year.
Have been vaccinated (Pfizer) but I don't think it was the vaccine that caused my heart problems. I think it is long covid.
I saw my gp in September for weird palpitations, skipping beats and feeling breathless and very tired and I had had a month of upset stomachs, with diarrhoea. She sent me for an x-ray which didn't show anything and did the usual tests for bowel cancer to rule that out.
I've had an ECG and a 24 hour monitor and an echocardiogram to try to get to the bottom of what's been going on. It's been a difficult year with significant change to my eyesight too.