SUMMARY

STEPS TO REPRODUCE
1. It just happens with default cursors, regardless of size
2. Also happens with installable breeze cursors
3. In display settings I have tried both Let legacy app scale and Let system scale
4. I have 2560x1600 ips laptop screen. Fonts are scaled to 1.5
5. Cursor size in settings: have tried 24 and 36 pixels

OBSERVED RESULT
teeny tiny cursors

EXPECTED RESULT
chosen size pixel

SOFTWARE/OS VERSIONS

Linux/KDE Plasma: 
(available in About System)
KDE Plasma Version: current version of Neon-unstable as of 8 dec 23
KDE Frameworks Version: current as of 8 dec 23
Qt Version: current as of 8 dec 23

ADDITIONAL INFORMATION
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By the way:
I see the same general problem in latest Plasma 5.27 on opensuse Tumbleweed. Except there using default cursor size results in proper cursor on Tumbleweed.  However, if I try to use a larger cursor, the cursor is too small.
SYSTEM INFO:
Operating System: KDE neon Unstable Edition
KDE Plasma Version: 5.90.90
KDE Frameworks Version: 5.246.0
Qt Version: 6.6.0
Kernel Version: 6.2.0-37-generic (64-bit)
Graphics Platform: Wayland
Processors: 16 × 13th Gen Intel® Core™ i7-1360P
Memory: 31.1 GiB of RAM
Graphics Processor: Mesa Intel® Graphics
Manufacturer: LG Electronics
Product Name: 17ZB90R-K.ADC8U1
System Version: 0.1