How do I raise refund request for wrong $25 payment on Apple Pay?

See the section “if you sent payment and want to cancel it” at If you have an issue with an Apple Cash transaction - Apple Support

if the funds have been accepted, you’ll need to ask the other party to return the money.

Apple Cash is a service that’s administered by Green Dot Bank. Contact an Apple Cash Specialist at Green Dot Bank by calling (877)-233-8552 or by calling 1-800-MY-APPLE

https://applecash.greendot.com/termsconditions/