Hmmm idk but it looks right in my eyes (?), but maybe it was necessary to look at it another way. See the example of "layers" in the .yyz project, I implemented the camera offset there
After uncommenting the PP_DISPLACEMAP_OFFSET code at the location you specified, I observed that it was also affected by the camera. Upon closer inspection, the PP_SINE_WAVE_OFFSET effect is actually camera-dependent as well. The shaking amplitude intensifies when obj_player moves. Please check if this matches the phenomenon I described? If so, does this meet your expectations?