Re Unfamiliar Payment

If you are the Family Organizer in Family Sharing, and someone initiates a recurring subscription the subscription is tied to their Apple ID, but you as the organizer must pay for it as explained when you created the Family Group.

Set up Family Sharing - Apple Support

One adult in the family—the family organizer—can set up Family Sharing for the group from their iPhone, iPad, iPod touch, or Mac. If you turn on purchase sharing, you'll be asked to confirm that you agree to pay for purchases initiated by the family members you invite and that you have a valid payment method on file.

They would need to unsubscribe from it on their account for it to stop charging you.

Hello,

Can you provide more info? Where do you see this charge? Is it in an email?

Take a look at these articles:

• Avoid phishing emails, fake 'virus' alerts, phony support calls, and other scams - Apple Support
• If you see 'itunes.com/bill' or an unfamiliar charge on your bank, credit card, or debit statement - Apple Support

If you received this charge in an email, DO NOT click on any of the links in the email. Check your purchase history to see if you actually made the purchase (See your purchase history in the App Store or iTunes Store - Apple Support). If you did not make the purchase, send the email to Apple (Phishing & Other Suspicious Emails). If you did make a subscription purchase, you can cancel it as described here: View, change, or cancel your subscriptions - Apple Support

If you accidentally made a purchase which was not a subscription, you can see this article: Get help with an item purchased from the App Store, iTunes Store, or iBooks Store - Apple Support