On April 5 I had to book a flight SFO-OGG-SFO. The outbound on 4/18 was wide open but the return on 4/21 was completely sold out in Y but I got the last seat (full fare). Now that I'm in Maui, I look at the 4/21 flight and this shows up:

F4 Y7 B7 M7 E6 Q6 V6 W5 S4 T2 K6 L0 G0 P4

The loads didn't look like this a couple of days after I booked my flight and the fare changed very little.

Are seats being sold back to UA from brokers?