I have gone through the links, and I still cannot find the answer to my question on what makes UPI “absolutely horrible when it comes to privacy” when compared to the other options in your original comment.

I still maintain that all practical means of digital transactions are inherently poor for privacy, regardless of the channel/medium. One is not less private than the other.

Of course, mediums like cryptocurrency exists which “promise” privacy while transacting. But they are not practical in India, and also do not operate at the scale of the options we are discussing about.

Also, I really appreciate responding back with links, but a line directly answering my question would have saved some time, especially since the links you shared are irrelevant to our discussion. None of the links actually do a comparison of the options or even state that one is outright better than the other. If anything, some of the comments in the linked forum posts only echo what I am saying about the lack of privacy across all digital transactions.