iMessage spam question

i created a unique iCloud email for my new iPhone SE. I've never used this email address anywhere except for iTunes and App Store setup. I only use Apple Mail on my iPhone to retrieve email for the account and never get any email to this account because I don't actively use it except for the Apple registration.

I have it set up in iMessage along with my phone number. I never have sent or received an iMessage using the ID only my phone number.

How is it possible to be getting Ray Ban sunglasses spam to my iMessages under these circumstances? I've long been hesitant to enter the Apple ecosystem but was convinced to do it by a friend. I had a Samsung before that and never got SMS spam once. Now I'm with Apple hardly 3 weeks and I'm getting iMessage spam that appears to be coming through my Apple ID associated email.

I am a hugely private person and feel somehow I've had my privacy violated, and am worried also about Apple Pay which I also set up tied to my new Apple ID.

I see lots of complaints on the internet about iMessage spam. Since I've been careful setting things up and have only used this email with Apple and it's their iCloud, can anyone explain to me what has happened and if I've had my information compromised?

thanks