SUMMARY

I'm trying the new Plasma 6 Beta and I believe I've found a regression. In Final Fantasy XIV (running via XIVLauncher.Core), clicking and dragging with the mouse (which turns the camera), then clicking again, seems to "reset" or "jerk" the camera -- almost as if a mouse movement was "queued up" and sent instantly after the single click? 

Repro video: https://www.reidwiggins.com/assets/kwin-report-repro-video.webm
KWin debug console video (1 reproduction): https://www.reidwiggins.com/assets/kwin-report-log.webm

STEPS TO REPRODUCE
1. Run a full screen game that doesn't capture the cursor and uses the mouse to control the camera. (Not sure if this is FFXIV specific or not -- I don't play other games that have this behavior.)
2. Click and drag the mouse, which moves the camera.
3. *Without moving the mouse*, single-click again. Observe camera jerk.

OBSERVED RESULT

Camera resets wildly to a top down view. (This would be the equivalent of dragging the mouse to the bottom of the screen, ~instantly.)

EXPECTED RESULT

Camera doesn't move, since a single click doesn't typically move the camera.

SOFTWARE/OS VERSIONS
Linux/KDE Plasma: 6.6.3-arch-1-1
KDE Plasma Version: 5.90.0
KDE Frameworks Version: 5.246.0
Qt Version:  6.6.1
Session: Wayland, with NVIDIA 545.29.06 driver 
Display config: 0,0 1920x1080; 1920,0 3440x1440 (no scaling or rotation) displaying the game
Installed via: kde-unstable repo.

ADDITIONAL INFORMATION

Moving the cursor *at all* after clicking and dragging seems to avoid the bug, which you can see in the repro video. Nonetheless, this bug makes the game effectively unplayable.

Additionally: FFXIV in-game System Settings -> Mouse -> "Limit mouse operation to game window" appears to make the bug much harder to reproduce (not impossible), albeit with the cursor now locked to the window. Interestingly, the KWin debug console input log doesn't appear any different with this setting checked.

This behavior did not occur in KDE 5.27 (as currently in the main Arch repos).