I believe it's arrhythmias that you've heard of. The incidence of carditis are, so far, incidental rather than attributed to COVID. It's theorized that carditis develops from overactive immune response, but that's not confirmed.
No, as you would expect with a virus, COVID can and does cause myocarditis, at a rate much higher than any vaccine, again, as you would expect from an active vs at most inactivated virus.
