My emoji selector use to be in colour, now most of the emoji show up as an empty box and in black and white?
I managed to fix it by installing ‘google-nato-coloremoji-fonts’ using yast.
Nice you solved it yourself.
Maybe next time provide more information. In this case we may assume you use a Desktop Environment, but you failed to explain which one (KDE, Gnome, …) and we can not read minds. 