The volume sliders slightly vary in width while moving the slider
This is the bug I intended to report first:
The volume sliders have a marker at 100%, and sliding near to it snaps to slider the marker, which is nice. However, the resulting value isn't always exactly 100%. Sometimes it's a few hundredths of a decibel off.
Then I realized that the cause for that is probably this other bug:
The volume slider width varies depending on the slider position, because the label to the right of the slider that shows the volume percentage and decibel value doesn't have a constant width. This variance probably makes the snapping work unreliably, because just when the slider snaps, the snap marker moves to a differnt place.