Re: post-COVID and aFib, I had an event a few weeks ago and I may have ramped it up too fast in my COVID recovery .. I did 100 miles and then some heavy rock climbing then took a nap and got an aFib on my watch during the nap. This was about a week after I felt pretty much better for normal activity. Anyway the moral is if you get COVID I would go extra slow in building back up. Also hydrate really well, in retrospect I realize I was very dehydrated. Now I feel completely 100% and am back to getting PRs at a similar pre-COVID rate.
I've already done tons of work-up on my heart, Holter monitor, seeing electrophysiologist etc and nothing super major so far.