While I wouldn't call what's happening phase anomalies, this kind of applies. Among other things the pinna does, pinna phase cancellation does create an FR dip in the treble, with its location depending on the angle of the originating sound source and being used for audio localization.
Rtings is the only objectivist audiophile group I know that actually tries measuring and publicly publishing the effects of pinna activation on FR, as opposed to the crowd blindly worshipping the Harman/DF curves:
(Note that this doesn't take into account other contributing factors to HRTF)
And if you look at quality treble measurements of IEMs or headphones with a reputation for sounding spacious, like the IER-Z1R, you'll usually notice a similar pattern of peaks and dips, particularly the respectably sized upper treble peak and the FR notches at ~5 kHz and ~10 kHz:
If you know exactly what to listen for, you can even EQ such features into other IEMs. My Moondrop Variations lacks depth because the 4-7 kHz range is smooth, so I apply a curve like this: