Color effects are applied to sprite even when OBJ window should disable them

[Vulcalien]

I've found a difference between hardware and mGBA.

In this test ROM, there are two sprites: 1. red square; 2. OBJ window. A color effect (brightness increase) is applied to all layers of the display.

Inside the OBJ window, color sprites are disabled. Outside, they are enabled.

On hardware, the red square is always drawn without applying the brightness increase, appearing fully red. Meanwhile, on mGBA the color effect is applied if the red square is OBJ 0 and the window is OBJ 1.

Expected behavior (same as hardware):

By pressing any button in the test ROM, the sprites are flipped, so that the window becomes OBJ 0 and the red square becomes OBJ 1. In that case, the behavior is accurate. I've not tested with different OBJ priorities, but I suspect that would yield some differences too.

Possibly #2809 is a result of the same underlying cause.