Summary and some discussion here: https://www.nextbigfuture.com/2023/08/myocarditis-heart-damage-in-1-out-of-35-covid-vaccinations.html :
"A new study of 777 people found that 22 had markers that indicated the mRNA-1273 covid vaccine caused myocardial injury in 1 out of 35 people. This is about thousand times more than prior estimates of myocardial injury. It would mean if 1.8 billion people in the world had covid vaccinations and boosters then 50 million would have had myocardial injury. This would usually be mild and transitory but if those people had strenuous exercise during this period they could trigger heart attacks. This would mean if 280 million people in the USA had covid vaccinations and boosters then you would expect about 8 million to have experienced myocardial injury from the vaccination."
Here is the source study: https://onlinelibrary.wiley.com/doi/epdf/10.1002/ejhf.2978
Dr. John Campbell discusses the new study: https://www.youtube.com/watch?v=cd_RTf_ForA&t=80s
I am not an expert but this study looks pretty legit to me: peer reviewed, relatively large cohort (777 people), respectable source and so forth.
If the risks revealed therein are in fact indicative of the population risks of these vaccines this is enormous news and a real "smoking gun" moment.
Edit: Here's a video of Dr. Vinay Prasad giving a very good explanation of the study (thanks to @fauxgnaws): https://www.youtube.com/watch?v=vveMHtVk_mY
The study doesn't mention a control group as it was focused on male versus female outcomes (20 out of the 22 were women, btw).
The author mentions that the rate is much higher than expected, and there is a high number of subjects which reduces the possibility of statistical clustering, but the lack of control group and counting people as vaxx injured unless they had an "alternative explanation" certainly justifies a study focused specifically on heart damage after jabbing.
They used a covariant matched control group, which is statistically valid but not as high quality as an in study control, of course.
And yes, the 'alternative explanation' thing needs more looking into; they threw out nearly half of the elevated troponin readings as not jab related without explanation. That is, even their alarmingly high reported myocarditis incidence may be conservative.
Oh, I've added a new video to OP. Dr. Prasad's analysis is excellent, if you haven't seen it.