A study claimed that those who get sick with COVID are sustaining damage to their hearts (myocarditis), due to studies that looked at elevated Troponin ICD codes in hospital patients. However, they would find the same elevated levels of Troponin in patients without COVID. This elevated level of troponin does not prove myocarditis was clinically present. The study says that there could have been cases of myocarditis, but they have no idea, as the ICD code use is contrived and inaccurate for this application.
You can find the latest research showing the incidence of myocarditis from the vaccine is higher than that from the COVID infection, here.