Unverified Apple Pay transaction on unknown iPhone 14 Pro

That's a scam.

If the activity was on your Apple ID / Account, then it would have nothing to do with Apple Pay.

If it was done through Apple Pay, then your Apple ID would not really be involved in the transaction and would require you to have allowed your payment method to be added to the Wallet app on this other iPhone, it cannot happen on its own.

And if you don't now and have never owned an iPhone 14, then this is total BS.

Also, Apple will not notify you Apple Pay transactions via message or email. They either go through in the moment, or are denied and you are made aware of it at that point, not via en email later.

This is entirely fake and can be ignored.

You can forward the email to reportphishing@apple.com.

Recognize and avoid social engineering schemes including phishing messages, phony support calls, and other scams - Apple Support

That’s a phishing attempt from scammers and its literally been reported 100’s of times if not 1000’s. 

Apple would never contact you. Your bank (issuer of card) would contract you. Banks do the exact opposite of the message you received. If they suspect fraud the transaction is stopped immediately. You have to call to verify the transaction, not call to stop the transaction. 

“Don't answer suspicious phone calls or messages claiming to be from Apple. Instead, contact Apple directly through our official support channels.”

”To report a suspicious SMS text message that looks like it's supposed to be from Apple, take a screenshot of the message and email the screenshot to reportphishing@apple.com.”

You can report phishing at these links and most importantly your local law enforcement.

• Identify legitimate emails from the App Store or iTunes Store.
• FTC Complaint Assistant
• FBI’s Internet Crime Complaint Center

Learn about how not to be a victim of Social Engineering.

Recognize and avoid social engineering schemes including phishing messages, phony support calls, and other scams - Apple Support

It is a long reported scam. Obviously you would not call the number provided in any such message. You can either do nothing at all or report it if you wish.

Recognize and avoid social engineering schemes including phishing messages, phony support calls, and other scams - Apple Support