Soundbar Q60r: Better sound quality with Bluetooth than with HDMI

[Palmrunner]

Soundbar HW Q60r connected to TV Q80r.
Usually it is connected via HDMI-ARC so that I can switch the soundbar on and off together with the TV. Unfortunately, I found that the sound with a Bluetooth connection is better and richer than the HDMI-ARC connection.

Is there an explanation for this?

Another inexplicable "feature" is that the equalizer is disabled when the TV and soundbar are connected via Bluetooth (and yet the sound is better).

[vishal0209]

I have a similar issue. I have a Samsung B670 soundbar and QN90B Samsung Qled TV. 
Sound with Bluetooth is louder and richer however with tv it is very ordinary.
did anyone find the solution?