Why has this object changed to a different color?

Solved: The normals were messed up.

I’m new to blender and a model that I’m working on has changed to a dark shade of blue. You can see that I created a plane in the upper right which is the color that I’m used to. I thought this was a problem with the “Show Weights” box being checked, but that is not the case. The shade of blue with “Show Weights” is also a lot brighter.

Edit: The box in the upper right is selected. When I deselect it, it’s a light shade of gray. The object in the middle is still blue when I export, then import it back into a new scene.

Edit 2: I guess it happens because of the way I created it. I followed the outline of a picture by adding vertices with ctrl-click. When I select the vertices and press F to add a face, it just comes out blue for some reason.