I've seen that here a few times lately too(and once where both greens were like this) , I guess the heat is causing something in the LED modules to overheat and fail.

Half of the LEDs in this module simply failed or not connected.
By the way, I saw in Israel also LED traffic lights with several failed LEDs (Our LED traffic lights are uses Dialights LED modules) as the light appeared in the module was uneven and dim.

I have seen the same, where the failure occurs in a random pattern inside the lamp module. Only seems to happen with the older units, the demo units that were installed around 4 years ago in a trial run.