Bose 700 background volume levels not constant
I recently purchased a Bose 700 soundbar with a Bose 300 Acoustimass module. While I'm very pleased with the audio quality with music reproduction, I'm facing some issues when it comes to movies or TV shows. The first impression I got when hearing to the soundbar was that it was 'too harsh', and that background noises were excessively amplified (something that was magnified by the Adaptiq calibration). I was able to counteract some of that by lowering trebles and upping the base, but the issue is still there, in some form.
But, on a more worrisome note, I realized that the volume level of background noise is not constant - in a quiet scene you could hear like very loud ambient sound (cars passing at distance, for example) - then, as soon as characters start speaking, the ambient noise goes down few notches (to the point that it's barely audible), and then comes back again when characters finish speaking.
I have not been able to solve this - at first I thought it was the source - e.g. the particular movie I was watching - but then I started noticing it in other sources too - with various connected devices. I can reproduce the issue regardless of how the soundbar is connected to the input device - either via TV through ARC, or directly (e.g. via optical cable) from the source.
I suspect that the soundbar is doing some processing of the audio, to make dialogue clearer (and, yes, i have "dialogue mode" turned off in case you wonder), something akin to some kind of dynamic range compression. Is this possible? Or is my soundbar defective and I should have it checked out?
Update: sadly it seems very related to the AutoGain feature described here:
Has nothing been done to rectify this issue after 2 years? At least a toggle to disable whatever DSP the soundbar is applying?