SUMMARY


STEPS TO REPRODUCE
1. Log into Wayland, see the cursor's size and compare to the size in Xorg session.
2. Open an unmaximized window with titlebar.
3. Hover the cursor over the titlebar (set aurorae theme to be not breeze, like breezmite or others) and off the titlebar area. Hover it over Dolphn, Calculator and some non-Qt app.

OBSERVED RESULT

Notice how size changes, it's normal over the titlebar or non-qt area, goes oversized outside the area. So basically, when you open Qt app like Dolphin and Calculator, an oversized cursor is gone only over the titlebar. When opening Firefox, Filezilla or any non-Qt app, the cursor is normal within the whole window (so titlebar and the app window), goes oversized outside of the window.

EXPECTED RESULT

Cursor's size should be correct, like in Xorg session, also not changing based on where it hovers over.


Operating System: Manjaro Linux 
KDE Plasma Version: 5.18.0
KDE Frameworks Version: 5.67.0
Qt Version: 5.14.1
Kernel Version: 5.5.3-2-MANJARO
OS Type: 64-bit
Processors: 8 × Intel® Core™ i7-6700HQ CPU @ 2.60GHz
Memory: 7,6 GiB

Additional information:

GPU - hybrid, but Intel used in wayland session:
    Driver: Intel Open Source Technology Center Mesa DRI Intel(R) HD Graphics 530 (Skylake GT2) x86/MMX/SSE2
    Driver's version: 3.0 Mesa 19.3.4
    OpenGL: 3.0


I can't make a screenshot, because screenshots doesn't work well on Wayland, and spectacle doesn't have most of its features (no way to trigger delay or enable cursor's capture).