KDE: not at all comparable to Slack's reach. Not an app. Not even cross-platform?

AMD's Radeon: admittedly, I have not used this.

VLC: hardly any UI. Mostly menu items.

VirtualBox: hardly any UI. Mostly menu items.

Edit: formatting.

I've used the Radeon control panel. I also use the Slack and Spotify apps all the time with no complaints.

The Radeon interface does not fit in at all with Windows (nor macOS or any Linux DE I've ever seen, for that matter) and is almost always glitchy for me.

The Radeon control panel is worse than any electron app I have used, often glitching/freezing.