...
have had myocarditis (inflammation of the heart muscle) or pericarditis (inflammation of the lining outside the heart) have a fever"
And THAT is precisely what the FDA is requiring them to study over the next several YEARS. Admitting that there are "serious" concerns about these inflammations.
Additionally, I'd wager that a big majority of people who have had either of these inflammations probably didn't even know about it, or at least, were never diagnosed with it for a variety of reasons.
Compare with the demand that all get the vaccine! No one is reading the fine print.