Ritesh Bhatia, a cyber security consultant, warns about two types of scams related to UPI transactions. The first involves the misuse of a person's phone number and UPI registration on another device. The second occurs when individuals are already being scammed and making payments. Bhatia emphasizes the importance of being cautious with the introduction of credit lines on UPI, as scammers can siphon off funds. He advises setting separate PINs for UPI and credit cards, setting transaction limits, disabling international transactions if not needed.