I tested this gradient image

as the cursor. It shows up perfectly fine on X11, but on Wayland, it shows up as just a red block with full opacity.

I don't really see anything wrong with the buffer creation. I'm not able to figure out what is wrong.

Here is my branch where I added the image to the example, but didn't get further https://github.com/eero-lehtinen/winit/tree/custom-cursor-gradient.