This is a peer user support forum. No one here actually has any involvement with the donation process. I understand it is managed by Mozilla on the projects behalf on a cost recovery basis, but that is as far as my knowledge goes.

However the donations web page has a contact us link which points goes to this page. https://donate.mozilla.org/en-US/help/ I suggest you ask them, however I only see a credit card, PayPal and GPay as options for payment, so I would guess you are limited to those choices.

I did click the gpay option and as I do not have any payment method set up in GPay, it did ask for me to set up a payment option.

As I had to Google UPI to even find out what this Indian payment system was, I can not see it being accepted. But you could ask.

I did search google which indicated that UPI can be added to Gpay as an account source for funds. It does not look like the Indian government allows most of paypal to function in the country, but I have not really spend much time looking as it really is not relevant to me.

Thank you Matt for your clean reply, Though my problem is not solved, but you have given a convincing explanation of the process. Thank you. My problem is I think it is deep-rooted with Google earlier payment modes, where i enlisted certain card details and may be due to that this prompt is coming. Thanks anyway.