When I go into System Settings/ Wallpaper there's no option to set custom wallpaper anymore. Also all my previous custom wallpaper settings have disappeared from Wallpaper in System Settings too. The top left box is black with a question mark in the middle. I can only choose from Apple build in wallpaper options. Just noticed this on Tahoe 26. Don't know if this function disappeared in an earlier version of the OS. Updated to Tahoe 26.1 and still no option to set custom wallpaper. Don't when this option disappeared.