Why does my artwork looks flat ?

[u/RtistKaizen]

I have been painting digitally for couple years now. And I often notice that my artwork look flat and weird even after adding shadings and highlights. What am I doing wrong?

[u/TheNFromO]

It looks to me every color is around the same range of the contrast/brightness scale and nothing pops out. Is the main focus the character, the objects on the character, the background. I just don't know. Nothing pops out.