Perhaps one of the mods here @Rakly3 can explain the system behind Quest Pro ...
So they have two glacier (black and white) cameras for high-speed motion tracking ...
And then they have one color camera that lays color on top of the combined black and white 3D images ...
And the passthrough doesn't work well for two reasons:
(1) Meta removed the Depth Sensor at the final stage of development for reasons not currently public
(2) Meta intends to release an update in the near future that will improve passthrough on the Quest Pro, to make passthrough more than a gimmick.