I too am experiencing the volume being unreasonable, either high or low. My device is an Xperia 10+ running Sailfish X 3.3.0.16.
With the speakers, the output seems to be fine, but with Bluetooth, the volume is way too low for media consumption and far too loud for phone calls.
I came up with a simple workaround in this thread for the Bluetooth audio for music playback, but when taking a call today, I had to switch to just using the phone itself, as the headset was unusable at minimum volume due to it being way too loud. (I understand my volume boost made this problem worse than it would have been, but I think even at normal volume, it would still have been twice as loud as it needed to be.)
While I think it makes sense to ideally keep all devices at the same volume level, it seems to not be universal depending on device or application used, and therefore some way to adjust the volume up or down for certain use cases would be a welcome change from my perspective.