System sounds slider at 0 by default, but sounds are played anyway
With Debian Sid/unstable, in a default GNOME Shell 3.36.3 setup system sounds can be heard. Under Settings → Sound in the section Volume Levels the slider System Sounds is on the very left, so 0. This is confusing. After moving the slider for the time, and then to the very left, no sound can be heard as expected.
I guess, this behavior means the default value is used, but it’s a confusing UI.