Created attachment 142051 [details]
Recording of me triggering accidental app preview switching

SUMMARY
If I hover a grouped app to trigger 3+ preview icons, then move the mouse towards a side app preview, and if the mouse intersects another app icon, the preview switches to that app.

STEPS TO REPRODUCE
1. Open 3 windows of one app.
2. Hover the app icon in the task switcher.
3. Move the mouse towards a side window.

OBSERVED RESULT
If my mouse trajectory intersects an icon on the side, and if on any frame, the mouse's current position lies on another icon, the previews switch to that app's windows.

(If your mouse moves *down* from the preview towards the app icon, the same thing can happen. However I'm not sure if this is something users do often.)

EXPECTED RESULT
Add a delay or a triangle filter (like Bug 434904) for switching apps in the task manager.

SOFTWARE/OS VERSIONS
Operating System: Arch Linux
KDE Plasma Version: 5.22.90
KDE Frameworks Version: 5.86.0
Qt Version: 5.15.2
Kernel Version: 5.14.8-zen1-1-zen (64-bit)
Graphics Platform: X11
Processors: 12 × AMD Ryzen 5 5600X 6-Core Processor
Memory: 15.6 GiB of RAM
Graphics Processor: NVIDIA GeForce GT 730/PCIe/SSE2

ADDITIONAL INFORMATION

I believe Windows 10 uses a delay before switching app previews.

Adding a delay for switching hovers may solve Bug 439363 as well. But oddly enough, when you hover an multi-window icon on the second row of the taskbar, Windows 10 displays the app previews *above* the entire taskbar on hover, but moves it down to *above the second row* on click. However, on KDE, clicking an app defaults to cycling its windows, so "moving on click" isn't achievable. However I think a delay is a good enough solution.