Increase in Y availability SYD-HKG

[RealtimeY]

I've been keeping an eye on CX flights in December and watched them apparently sell out in economy in the last couple of months.

This is what the availability looked like on CX SYD-HKG for December when I looked on 12 October.


Today, it looks like this. It looks like every flight is suddenly displaying Y9 (no new flights though). What is going on here? Were they holding onto seats, or are they now overselling?

 

[RealtimeY]

And EF just notified me that they've changed aircraft from A350-900 to A350-1000, so that answers it.