Why is one of my terrains lighter/brighter than the rest?

SO here I've just painted the terrain using a sand texture. On the right hand side is what it looks like normally, this is how it looks painted on the rest of the terrains and then on the left, you can see it goes super light. The grass is supposed to be a darker green too.. Everything on the settings is the same, I've compared its settings to the settings of the other terrains and everything seems in tact.. I'm not sure its the directional light because the environement and lighting is the same all over. So I'm a little confused as to how I can fix this. Hope someone has some insight in this! Thanks!