I just upgraded from Fedora 34 to Fedora 35 and now Plasma makes a little bubble popping sound every time there is a system notification. Is there a way to disable this? I only find Hardware->Audio when searching for sound settings and I don’t see anything about sound in the Notifications settings. Could I be missing a package?
Open system settings search for audio find play back streams and see the notification sounds and tune down the slighter to 0%.
It turned out that the sound was coming only for notifications from Evolution (yes, I have to use Evolution even though I am using Plasma). I was able to disable it from the plugins->“mail notification” settings. I tried keeping the audio settings window open and watching, but I never saw a playback stream appear for these notifications. Perhaps it was just too short.