Billing

1. This is a user to user forum. You are not addressing Apple. As users, we are not trying to take anything off your card.
2. Follow the steps here to find out what the charge was for: If you see 'itunes.com/bill' or an unfamiliar charge on your statement - Apple Support
3. The iTunes platform does not and cannot in any way create random charges you don't initiate yourself. So the charge needs to be result of something you specifically did. Either downloading an app that may contain a Free trial that renews into a subscription, or some in-app purchase in an app you already have or something else like that.

The app probably have a free trial or in-app purchase which you didn't notice in the fine print and it automatically started after the trial period.

View, change, or cancel your subscriptions - https://support.apple.com/HT202039 - Learn how to view your subscriptions that renew automatically, change your subscription period, and turn off Automatic Renewal." "If you don’t cancel more than 24 hours before your renewal date, your subscription might renew." Deleting an app does not cancel a subscription. Stopping the auto-renewal of a subscription only does that, it does not immediately stop the subscription, nor result in any refund.

This is primarily a user-to-user support forum; other Apple users like yourself.

See: If you see 'itunes.com/bill' or an unfamiliar charge on your statement - Apple Support