When we came to the lounge, we were asked if we wanted to be on the waitlist for the earlier flight but since we wanted to stay longer in the lounge, we declined. I heard the agents asked a lot of passengers arriving in the lounge if they were interested in taking the earlier flight and I guess at least 5 were moved to the earlier flight in the end (and probably got upgraded). Had they not been put to the earlier flight, I guess my flight would have been overbooked in Y and I would have been upgraded to Premium Economy