After you pay, open the payment details in your app (GPay, PhonePe, Paytm and others). Copy the 12-digit number called "UPI transaction ID", "UTR" or "UPI Ref No". Do not use the "Google transaction ID".
₹150
✓ Payment successful
Paid toMohandas Kasare
UPI transaction ID412345678901
↑ Copy this number
Google transaction IDCICAgL…
Sample screen. Your app may look a little different.