icon become grey

pls note firefox icon in below images.
View image: before normal icon
View image: after grey icon

the firefox icon become grey and stay grey once clicked. recall that there is no such problem in live cd env. small problem but annoying.
is there a fix? tks.

This is normal and intended behaviour: Selected icons are tinted in the current color scheme’s Selection Background colour to better distinguish them from unselected ones. You can see the same in dolphin f.e. as well.
And AFAIK there’s no way to turn that off.

But if you don’t like the current colour you can change the Selection Background colour in “Configure Desktop”->“Application Appearance”->Colors (Colors tab) to a different one.

I call it puke green on my PC, but will peruse the fix posted by wolfi323.

just click somewhere else within the plasma widget (or click another icon) and the firefox icon will return to normal. It is normal for selected icons to display this way.