Maybe you’re hearing the higher frequency harmonics generated by wind noise:
Pitched musical instruments are often based on an acoustic resonator such as a string or a column of air, which oscillates at numerous modes simultaneously. At the frequencies of each vibrating mode, waves travel in both directions along the string or air column, reinforcing and canceling each other to form standing waves. Interaction with the surrounding air causes audible sound waves, which travel away from the instrument. Because of the typical spacing of the resonances, these frequencies are mostly limited to integer multiples, or [harmonics](https://en.w
ikipedia.org/wiki/Harmonic), of the lowest frequency, and such multiples form the harmonic series.
Source: Harmonic series (music) - Wikipedia
I don’t know how Phonak does it but ReSound says the “Outdoors” program is most effective for wind noise and if you are in the more general “All-Around” program intended for speech indoors or any other programs you won’t do as well in wind noise. Are you switching to a Phonak wind noise specific program? Maybe the problem is using Autosense with Wind Block thrown in on top of that and somehow Autosense is messing things up? For ReSound with the omnidirectional settings for Outdoors, ReSound’s recognition and suppression technology (when last I checked) relied on the noise being heard differently in one ear than the other, the HA’s looking for this ear-to-ear noise variation, and preferential suppressing that, particularly if it were in the low-frequency range that you cite. I recall the ReSound explanation noting that other HA OEMs may use different methods but if any settings like ReSound’s were available to put into a manual Phonak program, maybe (in my ignorance) that might help.