You are in some deep denial. There is absolutely nothing unusual about getting heart damage and not knowing until experiencing a stressor that causes a heart attack.

I don't see why it would matter where it comes from

How can you say that after I explained why it matters? You are trying really hard to hold on to a belief. It's like one part of your brain had completely blocked information from another part of your brain.

it's the body's own immune response that's the mechanism behind the damage.

First off that is not entirely true. In the case of blood clots the pathology is believed to be caused by the blood vessel walls getting infected by the vaccine. When those cells produce the spike protien and start releasing them some of those protiens get stuck on the cell wall causing them to become unnaturally rough, which then stimulates blood clotting.

Secondly the immune response to the vaccine is very different than a natural infection. The former is full of adjuvants that throw your immune system into overdrive. That overstimulation is what causes autoimmune diseases to develop because it can cause your body to start attacking itself.

There is absolutely no reason for a respiratory virus to cause any immune system damage to your heart. The virus does not infect the heart.

The vaccine can infect the heart. It may not be likely, but it is possible.

No other respiratory virus has ever caused heart problems. The corona virus is not new and has been infecting humans for a long time. This particular one is just engineered to be more infectious.