being charged with an unauthorized payment

There is no such thing as an unauthorized payment. What is the reason you can’t download other apps?

If you were charged by Apple for something there are a few possibilities:

• You installed an app that required a subscription; the subscription is activated automatically when you download the app
• You purchased it from the app store (or subscribed to a service) and forgot you did
• Someone you share your phone with purchased it from the app store
• Someone you share your Apple ID with purchased it from the app store
• If you have a family sharing plan, someone in your family purchased it from the app store
• Your Apple ID was hacked and the hacker made a purchase from the app store - for this one see →If you think your Apple ID has been compromised - Apple Support
• The purchase perhaps had nothing to do with your iPhone or Apple ID. Someone compromised your credit or debit card and made a personal purchase from Apple.
• You were not actually charged for anything; the message you got was a scam to steal your identity - see →Avoid phishing emails, fake ‘virus‘ alerts, phony support calls, and other scams

The bottom line is that Apple never charges you for any purchase without authorization. So someone with access to your account must have made the purchase or subscription, if it wasn’t a scam message.

If it is a specific item on your bank or credit card statement see this link →If you see "apple.com/bill" or an unfamiliar charge on your statement - Apple Support

You can review all of your purchases as described in this link →See your purchase history for the App Store or iTunes Store - Apple Support

If it is a subscription you can cancel it here →See or cancel your subscriptions - Apple Support.

Note that subscriptions are not canceled when you delete an app; the subscription must be canceled separately from deleting the app.

If the charge was made in error you can request a refund here→Request a refund for apps or content that you bought from Apple - Apple Support

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, request refunds and update your payment method.

That has nothing to do with the unauthorized payment, unless you requested a chargeback through your issuer.

That message means that something about the payment method isn’t matching. Or it means that you just have to verify the payment with the side button on your phone.