Virtually every person who has gotten a blood clot from J&J has been a woman of menstrating age. Sure, it's happened in men, but virtually no man.
The fact that they felt the need to mention this, on their website, and not any other random side effect speaks for itself.
Heart problems related to the vaccine are associated with the mRNA vax, but (while exceptionally rare) you can still get them in.
https://www.bmj.com/content/373/bmj.n1244/rr-10
So part of the reason we've seen less myocarditis from J&J is WAY fewer people have taken it compared to the mRNA versions. However, Astra Zeneca works the same way as J&J and has been used by tens of millions of people all over Europe and the UK.
https://www.bmj.com/content/373/bmj.n1244/rr-10
https://www.healthline.com/health/as...#how-they-work
It's very very rare to have this problem with AZ or J&J but it has happened. My preexisting medical conditions are probably why I had this problem.