I suddenly got similar symptoms since getting a nasty version of strep throat last October. Notably I had an elevated fever (>102F) for quite a few days straight. I've never had COVID but I did get the mRNA vaccines + booster.
Since that fever, my heart goes into light arrhythmia all too frequently. It used to be maybe once or twice a year I'd notice 1-3 seconds of "off-beat" heart pattern. All of of a sudden it's a few times a week. I'm also getting older (entering mid 30's now), live in some of the worst air quality in the US (next to a bunch of chemical plants which are frequently releasing quantities of ethylene oxide/mercaptans/styrenes/acrylates/etc), and haven't been exercising much at all the past few years (largely due to air quality issues). My diet isn't the best either, but I incorporate a lot of fresh salmon which keeps my blood pressure down, triglycerides low, and HDL really quite high.
There's probably more I could do to help myself using just current medical knowledge, but additional knowledge and medical practices are always, always welcome IMO.