Not sure if it's the case elsewhere as well, but at least in India, email address on amazon orders are accessible to sellers if you made a purchase from a seller. I have had sellers reach out to me right after buying something from amazon, offering an incentive for a review.

Further, customer support agents can pull up your details as well. At least when there is an active ticket. I was reached out by one of the support executives confronting me from his personal mobile number after I left poor feedback for a chat interaction.

Amazon has little or no respect for data privacy especially in regions where there are no strict regulations that can cause them monetary loss through fines.

Since you mention it's in UK, I am surprised this is the case.