SUMMARY When using kwin_wayland, windows which use transparency with background blur flicker during screen updates and the mouse point may leave square blocks of trails in the background color (as if no background blur was used). This can be observed both with NVIDIA and Intel. Disabling background blur in konsole fixes the issue but other windows may (and even the plasma panels) may still be affected, tho the problem is most prominent with konsole. STEPS TO REPRODUCE 1. Enable background transparency/blur in konsole 2. Update screen contents in konsole and move the mouse point around within the window 3. Move the window around OBSERVED RESULT Trails of background-colored blocks are left behind the mouse cursor, konsole window contents may flicker heavily. EXPECTED RESULT No flickering, no mouse trails. SOFTWARE/OS VERSIONS Operating System: Gentoo Linux 2.13 KDE Plasma Version: 5.27.4 KDE Frameworks Version: 5.105.0 Qt Version: 5.15.9 Kernel Version: 6.1.26-gentoo (64-bit) Graphics Platform: X11 Processors: 20 × 12th Gen Intel® Core™ i7-12700K Memory: 31.1 GiB of RAM Graphics Processor: NVIDIA GeForce RTX 3080 Ti/PCIe/SSE2 Manufacturer: ASRock Product Name: Z690 Pro RS ADDITIONAL INFORMATION Also happens with Intel (Gen3 iGPU): Intel(R) Core(TM) i5-3470 CPU @ 3.20GHz But usually, flickering cannot be observed with latest Plasma version but mouse trails are still present. The flicker problem mostly went away after I bumped the iGPU shared memory area from 32 to 512 MB (and it also fixed the lockscreen freezing until I "loginctl unlock-session" from alt+F2 and restart kwin which is not feasible with wayland). I disabled konsole background blur on that iGPU for now because it really hurts desktop rendering performance, so it less a problem on that iGPU anyways for me which mostly lefts us with the issue on NVIDIA.
Created attachment 160817 [details] Squares appear when cursor is above transparency I can reproduce this on Plasma 6, but not on Plasma 5. It also depends on window updates. In the video, the artifacts don't appear with OBS open, appear and disappear with a Konsole window updating in the background and are always visible when no windows are updating. Operating System: KDE neon Unstable Edition KDE Plasma Version: 5.27.80 KDE Frameworks Version: 5.240.0 Qt Version: 6.6.0 Kernel Version: 5.19.0-50-generic (64-bit) Graphics Platform: Wayland Processors: 6 × Intel® Core™ i5-9400F CPU @ 2.90GHz Memory: 15.5 GiB of RAM Graphics Processor: AMD Radeon RX 570 Series
*** This bug has been marked as a duplicate of bug 455526 ***