there's an article today on The Athletic about a ice hockey player who passed away in europe, bratislava i think, last month from a heart issue.
the article is mainly an interview with his team mate, who was diagnosed with myocarditis 6 years ago, and had to miss 2 years of hockey whilst it was treated/recovered. he collapsed in 2015, and is only still around as the hospital was literally spitting distance from his team hotel, and that a teammate heard him collapse in the shower. he'd collapsed three weeks earlier, was checked by the physios, and given the green light to carry on.
the article then talked about another hockey case, with a player in america being diagnosed with myocarditis after contracting covid in 2020. it gave him a mild inflammation, but it was only due to his covid positive status that forced his club to do mandatory heart tests, and that picked it up the more serious damage.
in all three cases they talk about mild inflammation of the heart being enough for an elite sportsmen to then develop a serious problem. two of the cases are long before vaccine rollout. in the third case (the player that passed away) the article doesn't mention his vaccination status, but the family statement did say covid was not a factor.
the main point of the article is that myocarditis is not routinely screened for (there is no diagnostic test), even though it is the third highest cause of sudden death in young people, most commonly caused by viral infections.
even without (legitimate in my mind) vaccine questions, it is not a surprise that we are aware of more issues given we are in the middle of a pandemic that causes scarring of the heart. recent data shows ~2% of positive cases result in some cardiac issues, with length of time to recover unknown. certainly the players interviewed are scared about the future, given so many elite athletes are testing positive, and then returning to training within a couple of weeks with no consideration to effects on their heart.
which is a long way of saying we haven't seen the last of these stories sadly.