I had Covid early in 2020 and immediately noticed missed heartbeats at a fairly constant rate. Quite a common after effect I've been told. Cardiology put me on a Holter and told me I had sinus node disease and second degree heart block and inserted a pacemaker to stop bpm going too low whilst asleep.
They said the missed beats (11%) were nothing to worry about, they could give me tablets to try and stop it if it made me anxious. I declined the meds.
Early 2021 I started taking 200mg of Magnesium Citrate daily and after a few weeks the missed beats stopped. But 6 months or so later they returned - but I still kept taking 150mg of Magnesium Citrate.
Then about 5 months ago the missed heartbeats stopped again and I haven't had a single missed beat since then.
Of course the missed beats could return but I think that the Magnesium Citrate is beneficial and will stay on it permanently. I think it works for some but maybe not for others - but well worth a try.