Asked Sony Support and they said no, its unencrypted, unfortunately. So if you use this headphone, everyone can listen in.

Hi Fseidl,

When you connect the transmitter unit to the headphone jack of the A/V unit, set the volume on the A/V unit as high as possible, but not so high that the sound signals are distorted.
Tips for better reception can be found at the following link: https://bit.ly/41t7LBH

Sony Europe