Created attachment 104844 [details] Samples as seen by placing the cursor next to the preview in systemsettings. Most visible when viewing "Breeze" cursors on a white or light background. Pixels which are white (or light) which are semitransparent will appear darkened. When taking screenshots, if on an X11 system, the cursor will appear 'as it should' in the screenshot. If on a Wayland system the cursor will faithfully show the issue in the screenshot. This was tested on an X11 machine running Nvidia Prop drivers, and a Wayland Intel machine. I have seen it on others. This bug has been present for years, it is not new; it is only because my Wayland session took an accurate screenshot that I'm able to report this.
At least on X11 there is nothing we can do. This is completely handled inside X11 and the graphics driver. The window manager has no influence on it. Also on Wayland we do not have any hints on how the blending looks like which will be used by the drm library and cannot influence it at all. All we can do is provide the cursor image and the position. Everything else is handled by the graphics stack below. I'm sorry, there is nothing we can do. The only solution is to adjust the cursor icons to be prepared for the blending algorithms used by the graphics stack. But I cannot tell you which one it is.
I've reported this bug upstream. If they recommend a solution or request more information I'll relay what they say here.