SUMMARY Some KWin effects badly interact with each other, I'd say incompatible for some scenarios. Especially Window Open/Close Animation don't play nicely with blurry background, and semi-transparency while Alt (or Meta) + dragging windows around with a mouse. Video showcases some of these glitches: https://youtu.be/pGp53kkyXrY STEPS TO REPRODUCE 1. Enable effects like in my video. 2. Open System Tray popup (full representation dialog). 3. Hold Alt (or Meta?) and press on it, then release OBSERVED RESULT Popup turns semi-transparent, rapidly loosing its blurriness. On release it flashes with lighter-than-it-should-be background while regaining blurry background with an animation. Same glitch can be observed on tooltips. EXPECTED RESULT Popups should animate smoothly between transparency levels and blurriness, no matter target values are or which effects are enabled. SOFTWARE/OS VERSIONS Operating System: Arch Linux KDE Plasma Version: 5.24.80 KDE Frameworks Version: 5.92.0 Qt Version: 5.15.2 Kernel Version: 5.16.10-arch1-1 (64-bit) Graphics Platform: X11 Processors: 8 × Intel® Core™ i7-6700HQ CPU @ 2.60GHz Memory: 15.6 GiB of RAM Graphics Processor: NVIDIA GeForce GTX 970M/PCIe/SSE2