The study is not saying that 95% of people who get COVID do not experience heart damage. It is only saying that 95% of people who get COVID did not have a heart

The study is not saying that 95% of people who get COVID do not experience heart damage. It is only saying that 95% of people who get COVID did not have a heart-related acute event in the time period examined. That doesn't mean they had no heart damage at all. Their hearts were not directly examined. The point of this study was to assess whether people who have had COVID are at increased risk for heart-related problems (and the conclusion was that yes, they are), not to assess what percentage of them had actual heart damage.