Many of the low cost (70¢) or free services and items you see on TikTok, Facebook and Instagram are actually a subscription that auto renews on a weekly, monthly or annual basis until cancelled with the merchant. The subscription authorizes the merchant to automatically charge your Apple Pay method.
The mechanics behind Apple Pay are different and more secure than using your credit card. The merchant does not have your actual card details (card number, expiration date and security code). They do have an encrypted token that they submit to the payment network (Visa, MasterCard, etc.) to initiate the payment.
You’ll need to contact the merchant and cancel the subscription to cancel the authorization and any future payments. Any refunds would come from the merchant. If the merchant fails to cancel, you can start a dispute by calling the phone number on the back of the credit card you used.