audio sources below the listener exibit a large sudden transition between filter states when passing directly over or just to the sides of them (even with bilinear filtering) due to what im assuming is a "hole" in the HRTF data.

providing a custom .SOFA file can "fix" this pointing to a problem with the defult HRTF.

an example can be found here https://vrchat.com/home/world/wrld_cd04125f-3c36-43f9-93c4-999674297552. (turn right from spawn and cross the bridge while looking straight ahead)

I should mention however this may not be fixable on VRCs end since this appears to be an inherent issue with steam audios HRTF as this occurs in edditor and in valves own games like CS2 but i thought i'd at least bring attention to this issue regardless.