I mean this sounds like an edgecase, which is good tradeoff for the ~billion of people who this system is designed for.

Essentially UPI was there to stop the industrial fraud and money laundering that was going on india. I have not actually checked the efficacy of this though. The last time I checked was when modi made the largest bank note not legal tender.

That part aside it does sounds like VAT (a 20% sales tax on all purchases) but for transactions.