That indeed is a Bluetooth feature that supposedly makes audio quality better by only lowering the volume using the actual speaker driver instead of doing it digitally and potentially throwing away some quiet sounds. In theory, doing it this way is always better and should be preferred. In practice, many devices handle it terribly.
If you want to turn the feature off, you can enable developer options on your phone (settings -> About phone -> tap Build number a bunch of times) and turn off absolute volume. That will give you back software volume control with fine-grained adjustments.
That indeed is a Bluetooth feature that supposedly makes audio quality better by only lowering the volume using the actual speaker driver instead of doing it digitally and potentially throwing away some quiet sounds. In theory, doing it this way is always better and should be preferred. In practice, many devices handle it terribly.
If you want to turn the feature off, you can enable developer options on your phone (settings -> About phone -> tap Build number a bunch of times) and turn off absolute volume. That will give you back software volume control with fine-grained adjustments.