EDIT: A number of users suggested that this effect rises from the colour banding present within Apple’s wallpaper that comes prepackaged with MacOS Sonoma.

After capturing a screensnip, I can confirm that this effect is generated by the launchpad screen overlaying the colour banding in the wallpaper.

EDIT: A number of users suggested that this effect rises from the colour banding present within Apple’s wallpaper that comes prepackaged with MacOS Sonoma.

After capturing a screensnip, I can confirm that this effect is generated by the launchpad screen overlaying the colour banding in the wallpaper.