GRU-JFK flight in Jan 2023 on 77W (one way). Paid $2071 for biz. First was being sold for $6321 at time of booking. After ticketing, app offering $1200 to move up. While tempted, there are 2 of us so that is $1200 to move up from a J to F lie flat seat with some more amenities, though the majority of the 9.5 hour trip will be spent sleeping. Plus we're already booked in the mini 2 row J cabin which will be cozy as it is.
Makes sense to stay put. What I’ve found is similar to what you’re seeing. There’s a very specific delta between J and F on the app. I have an upcoming LAX-JFK flight. The J to F fare difference was nearly $2k, but the app offered $377). I took it because I’ll take advantage of afternoon FFD before a connection and prefer the solo seat. Pre FCM, I’d apply miles to upgrade (no SWU since I booked into non I class).
As
Chicago747 noted, some of the fares are priced very high in the hopes that a few will bite, which will offset the “discounted F” offered via the app (and boost margins in general).
I have a BOS-MIA trip about a week from now. When I looked last week, generally J7 across the board and the fare difference was 450+. Looked this morning on EF before booking and nearly every flight of the day is now J0. My hunch is that there were a lot of people who took app offers.