How does UPI work?

Hello Dear Community,

I’m looking to learn more about how UPI payments work and have some questions about user flows in certain situations.

Recently, I visited India and noticed that their payment system is very advanced compared to Western countries. They use a system called UPI (Unified Payments Interface).

Almost everyone uses mobile apps like PhonePe, GPay, and Paytm to make payments almost everywhere! There's no need to carry bank cards.

Here’s what I’ve learned so far:

How UPI Payments Work
Setup:

The user has a bank account and a mobile number.
They download a UPI app (e.g., PhonePe).
The user signs up using their mobile number and receives an OTP (One-Time Password) to verify it.
They link their mobile number to their bank account by entering basic bank details.
The app verifies this with another OTP sent by the bank to confirm the linkage.
Making a Payment:

The user opens the app and scans the recipient's QR code.
The app displays payment details.
The user confirms the payment, and within a second, both parties are notified of the transaction status.
My Question
If the mobile number linked to the UPI account is reassigned to a new user, can the new user access the previous owner’s bank account funds?

I’d appreciate any insights or additional information on this.

Thank you!