I was once at the very back in Y on a domestic Chinese flight. When I opened the tray table it promptly fell off! Astonished, I pointed this out to a FA (admittedly, I was cheekily hoping they might upgrade me as the flight was very full). They moved me to the front of Y, and I spent the entire flight with the back of my seat being constantly buffeted and moved about, which was extremely annoying. Eventually I turned around to ahem, "resolve" the situation to discover that the tray table was being used to store a baby, hence the amount of movement.
Probably a good job I didn't recline the seat, in hindsight... Perhaps it also explains why the other tray table was broken!