Why is "Mail" showing up in my iCloud back up, when I deleted it when I first set it up?

I set up my iPhone the way I prefer it, and performed a back up.

Then, a week later I logged into my iCloud to see how many emails I had in my icloud mail.

I deleted them, and then went back to my device which has NO mail app anywhere on it, but now in my iCloud, there's a Mail icon. I will back up my iphone, and even though there's mail in it, since I deleted the app on my iphone my back ups stay with zero data backed up in Mail.

I really don't want to have the app I deleted from my iPhone showing up in my icloud but even the 5 people I've contacted at Apple don't have any idea what to advise I do.