So it begs the question …
If 5 years ago we hadn’t heard about it, and now it’s common speak, what changed?
You just proved my point.
Because it became something that was getting press?
IIRC the myocarditis was being reported as a common issue with covid before the vaccine ever came out [edit - apparently you were at least11 times more likely to be diagnosed with it after covid and no vaccine] and not really being paid attention to by most people, but once the vaccine came out it was latched onto as a sure sign the vaccines were bad because "we had some cases after the jab", completely ignoring all the cases before the vaccine, or that myocarditis is not pleasant but in itself is not actually a particularly major issue from memory (IIRC most cases clear up on their own after a while and many people will never know they've had it with an infection unless they need to see a doctor who catches it).
It's like "all the athletes having heart attacks now" nonsense, when in reality they were having them years ago, it's just that since a premier league player had one literally live on TV long before covid, there has been a really big push to raise awareness of it, which also leads to "why are we seeing defibrilators in public places
now" 'question', which ignores the fact that they've been gradually rolling them ever closer to the general public for literally decades*, especially after a schoolboy died of a heart attack whilst playing football at school (pre covid I might add) which led to a campaign to get a defib in every school, then in every sports centre etc, then trials in other public places like major shops and bars, and they've now hit the point where they're both easy enough for any idiot to use one and cheap enough you could probably require them as standard first aid gear in many medium size workplaces.
*Literally every time they've made them smaller, cheaper and most importantly easy to use they've moved them a step close to the public, at the rate they're going in another decade or so I suspect they might become mandatory for any employer with over something like 25 staff or any business of certain types in much the same way employers and businesses are already required to have specific levels of first aid gear depending on their size and what they do.