IMO, I'd think so. In 2020, when the inbound caps were very low (I don't know how low they were in comparison to the news today) Y pax were constantly booted from flights.
From an airline revenue standpoint as well - to me, it makes sense. The airline can only bring in, say for discussion's sake, 10 people. Then they better bring those 10 people in the highest possible fare, so that the airline can make some money .. if they bring in anyone in Y, even if paying the highest possible Y fare, it wouldn't be close to a J or F fare for the trip.
My mates have been through instances where if they were booked on Y, they were told by the airline that their flight is cancelled due to low loads. But after a while they got another call from the airline offering to fly them if they chose to pay for a J or F seat. I think this was Emirates, can't remember. Same story with QF QR as well, I'm told
Some mates have got their call that flight is cancelled and in the same call, they were offered a seat if they can pay extra for the J or F seat.
And all the J seats were in the $4K to $5K mark and F was in the $7K mark one way into AU
One of my mates had actually paid for a Y seat and they paid the difference in the airport to take a J seat as he desperately wanted to travel
There was a point in time in 2020, when anyone I know wanted to travel overseas I strongly recommended they be ready to shell out $$ for J seats at a minimum