Can I use my email as a user ID when making a payment?

Question

Electronic commerce

In general, it was supposed to send the user's email as one of the get parameters for the payment order so that, upon successful completion of the payment, it can be found and take the necessary actions. Question - is this considered a breach of privacy or something like that?

Answer 1

https://habr.com/en/post/327892/
it's easier to generate an ID