SUMMARY

AFAICT, there has never been an easy way to disable sound notification for all/most of the events. However, it was OK before since the per-event notification setting are very easy to see and change. It takes a single key press or click to go from event config for one program to the next and the icon makes it clear at a glance which one potentially have sound on.

However, since a few versions ago (I only noticed this when I want to change this setting again after getting a new computer) the per-event config is now in its own popup window while leaving a lot of empty space in the parent window that can easily contain the event config even for the smallest window size allowed. Given this, I believe the event config should be put back to the parent window instead of having to be it's own window (allowing it to popup when accessed from somewhere else (if that's the goal) is certainy fine and AFAICT the two can coexist with little duplicated code).

SOFTWARE/OS VERSIONS
Linux/KDE Plasma: ArchLinux
(available in About System)
KDE Plasma Version: 5.20.4
KDE Frameworks Version: 5.76.0
Qt Version: 5.15.2