Bug 483480

SUMMARY
Using a high quality / large sized image (for reference, I was using this image: https://unsplash.com/photos/galaxy-digital-wallpaper-rCbdp8VCYhQ) as a skybox on the Cube effect seems to make the effect unstable, make the screen go black, distort and cause some other freaky visual glitches, including not render on both monitors if a second display is connected. Even if you recover back to desktop from a broken Cube effect being used, this seems to also break some other desktop effects (most notably Overview) resulting in the screen going black and distorting until clicked back onto the desktop.
This can result in a full system lockup, and in some cases, Cube can render correctly but will delay a decent amount of seconds before appearing, in this delay, the screen goes black till Cube correctly appears.

STEPS TO REPRODUCE
1. Enable and configure Cube to use a large sized image as a Skybox on weaker hardware
2. press Meta+C 

OBSERVED RESULT
Various visual glitches are caused by Cube leading either to a system lockup or if recovered from, causing most desktop effects to make the screen black out until the session is restarted.

EXPECTED RESULT
Cube either renders correctly with no / little delay or warns the user that the effect may be unstable with the image provided for the skybox. (maybe entirely prevents the image and falls back to a plain colour?)

SOFTWARE/OS VERSIONS
Linux/KDE Plasma: Fedora Linux 40 KDE Plasma PreRelease
(available in About System)
KDE Plasma Version: 6.0.1
KDE Frameworks Version: 6.0.0
Qt Version: 6.6.2

ADDITIONAL INFORMATION
Additional Hardware Information for "older / lower end hardware":
Graphics Platform: Wayland
Processors: 4 × Intel® Core™ i5-6267U CPU @ 2.90GHz
Memory: 7.6 GiB of RAM
Graphics Processor: Mesa Intel® Iris® Graphics 550
Manufacturer: Apple Inc.
Product Name: MacBookPro13,2
System Version: 1.0