WB FO normally goes senior to NB CA. However, a lot of countries essentially lock up flight crews in their hotel rooms for their entire time off. You can only leave the room if you smoke; I've been told that a lot of WB crews have taken up smoking.
Imagine going to Sydney and being locked in your hotel room for 40 hours with a guard outside of it. And your meals left at the door.

Once everything goes back to normal, you won't see WB FO going junior. And while some talk about how bad WB reserve is, I spent a decent amount of time on WB reserve as a commuter. It wasn't bad. I'd still be doing it if it paid as much as NB CA.