I doubt they are related; Apple doesn't share your email with anyone. However, did you use Wi-Fi at the cafe? Did you sign in using Wi-Fi, or get or send any email using their Wi-Fi?
As another possibility, Apple Pay is tied to a credit card; it has a "secret" credit card number, but that number doesn't change. So if you use Apple Pay in 5 different stores they all charge to the same number. If you entered your email address in any of them (for an email receipt, for example) then the credit card processor has your email address. A lot of small businesses use Square as their credit card processor, and email receipts are one of the features available for customers when you charge at a Square-supported business.