Just noticed this on AI-FR website, which wasn't present earlier (bolding mine):


"YQ is no longer chargeable on international award tickets. Only non airline taxes are to be paid plus miles.
Flying Returns members can also redeem miles for upgrading the eligible paid class tickets in domestic and international network of Air India.
The miles required for economy to business class upgrade depend on the RBD/Booking class of the Economy class ticket to be upgraded and range from 60% to 190% of normal economy class redemption miles for that sector."


60% - 190% !! Previously it was a flat 75%.
Huge devaluation in most cases of booking classes then.