I was just charged $76 and I don’t know why

This is a user to user support forum. No one here can give a definitive explanation or change things for you.

Review recent purchases at https://reportaproblem.apple.com/ or check your purchase history in iTunes and view your subscriptions or check for an iCloud storage plan. If you are the organizer of a family share check for purchases by other members.

See also If you see 'itunes.com/bill' or an unfamiliar charge on your statement - Apple Support and About payment card authorization holds from the App Store or iTunes Store - Apple Support.

If you cannot identify the payment then perhaps you are looking at a phishing email. See Avoid phishing emails, fake 'virus' alerts, phony support calls, and other scams - Apple Support.

If there really have been purchases that you didn't authorize, or you've entered your Apple ID credentials at a fake Apple portal, see If you think your Apple ID has been compromised - Apple Support, change your Apple ID password, and if possible turn on Two-factor authentication for Apple ID - Apple Support.

See also Use Screen Time to prevent purchasing on your iPhone, iPad, or iPod touch - Apple Support.

• If there is no evidence of a charge on either your iTunes or bank/credit card accounts this is likely to be a phishing exercise which you should ignore.

• If there is a charge shown under your iTunes store account and it relates to misuse of your Apple ID then you need to start a conversation with iTunes Store support to get it cancelled and refunded, change your password, and enable two-factor authentication if at all possible.

• If it isn't connected to your own Apple ID but funds have gone from your bank or credit card account that purport to be from iTunes then the account has been compromised and you need to deal directly with your financial institution.

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See each of the steps in the following instructions. They include information on contacting Apple Support if the other steps don't help: If you see 'apple.com/bill' or an unfamiliar charge on your statement - Apple Support

If the only indication of the charges is from an email or text, be aware that it may be a phishing attempt to get you to log in to a site that appears to be Apple and divulge your password or credit card information. See: Recognize and avoid phishing messages, phony support calls, and other scams - Apple Support

and Identify legitimate emails from the App Store or iTunes Store - Apple Support