Air India DEL-IXL bid for upgrade to business 3k for passenger (2 pax) from economy and it cleared.
Economy was around 5k per passenger and business is 15k.

Vistara IXL-DEL upgrade fixed pricing from Economy to Business 9k.
Economy was around 6k and business is 16k.

Its funny how Vistara calls it an offer. Same experience with flights between DEL, BOM, PNQ, BLR. When you do the math, the pricing of the offer is the same as paying a business class ticket nearly all the time moreover points wise you only get the ones of your original booking class.