Any time you’ve got anomolous light/dark faces, there’s a good chance your normals are backwards.
Select the face, F9 to get the correct panel, as shown in your second screenshot.
See the “Draw Normals” botton in the bottom right panel, “Mesh Tools 1”? Click that on, and depending on your scale, you can increase the “N(ormal)Size”. Rotate the view a bit and you can see which normals are sticking out (i.e. facing outward).
Most likely the bad face will have the yellow “stick” pointing inside the model. In the panel “Mesh Tools” click on “Flip Normal” and all selected normals will flip direction. If you have a simple model without “inward facing faces”, you can also select all and type Control-N to set ALL normals to outward facing. Might not work with some of your bevelling though.