Do you have any evidence to support that assertion? I first learned of the issue from the scientific community tracking the data collected by the public health community.

Here’s an example of what that looked like in June 2021, covering developments in May, just 5 months after the first country in the world had approved the vaccine (UK, 2020-12):

https://www.yalemedicine.org/news/myocarditis-coronavirus-va...

Similarly Israel’s public health agency’s report was covered in June 2021:

https://www.reuters.com/world/middle-east/israel-sees-probab...