So this is the real reason having your email exposed is a potential issue. It's always about the platforms, goods, and services your personal information is connected to when these leaks happen.
If you're not using a burner account then everyone on that list as your email address, your first name, your last name, and knows you're a customer of a Peptide testing company that only tests about 7 products. That gives them enough information to extrapolate something about your purchase history.
The risk of negative repercussions may be low, but it is a significant breach. That said I absolutely understand why some people will continue to work with them.