Charges

One possibility is that it is for iCloud storage that was upgraded to the 50GB plan from the free 5GB plan. That is not listed with subscriptions. Cancel upgraded iCloud storage by downgrading to the free 5GB plan. See instructions in the following Apple article: Downgrade or cancel your iCloud+ plan - Apple Support

If that doesn't help, be aware that this is primarily a user-to-user support forum; other Apple users like you. We don't have access to information about charges to your account. Apple has a support article about charges — see each of the steps in the following instructions. They include information on contacting Apple Support if the other steps don't help. See: If you see 'apple.com/bill' on your billing statement - Apple Support