You are not hearing the 150kHz directly, you are hearing effects of the PWM tracking for controlling the output voltage. You say you are using a shielded inductor with potting, so that’s probably where the noise is coming from—the interface between the two parts (inductor and shield). Try using an unshielded inductor to see if the noise goes away. If you need a shielded inductor for that part for other reasons, try using a toroidal inductor instead (it is self-shielding for generating external B-fields, not for being immune to external interfering B-fields).
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MB2-423
MB2-498
MB2-633
MB2-634