So quick update. I got a replacement device and have to set it up tonight.
My “genius” was trying everything and went through all the diagnostics, from software to hardware, with the focus on the speakers. It was so loud, so he went to a quit room to listen to the sound. After a few minutes a few other colleagues were interested in this case.
Everything was fine with the tests, but everyone heard that sound. One guys suggested, that it has something to do with the magnets inside the speaker or maybe there are some bad alignments inside. Either way, they tried everything and were pretty clueless what causes that sound.
They wrote it down and will report it back internally.
I will report back, if the sound is still there on my replacement phone.
I couldn’t replicate that sound in the store because of the loudness there.
The sound in the camera was declared as normal sound because of the stabilizer and everything else inside the camera module. So it should be fine.