Do not pay

If the payment was made by mistake or due to some issues, you are able to report and your cost may be payed back.

How to do it, please check the link Request a refund for apps or content that you bought from Apple - Apple Support

When you look at an app in the app store the description will say whether it requires a subscription or has in-app purchases. The app may be free, but it can have a subscription. Once you download the app the subscription starts, usually with a free trial (but not always). But it is your responsibility to read the terms of use for the app before deciding to download it. A truly free app with say “free” on the download button. An app with in-app purchases or a subscription will say “get” on the button rather than Free. And paid apps will have the price on the button.

Here is a one-stop link for billing questions→Subscriptions and Billing - Official Apple Support. You can review your purchase history to see what you were charged for, cancel subscriptions and request refunds.