Hey Breutus, long time no talk.
Your leather is bleached out, it has lost most of it's zooxanthalle and that is why it's a whitish green.
The brown spots are the returning of zooxanthalle to the corals tissue.
You might have got a "Neon Green Leather" according to some vendors, but most leathers do turn a shade of green under the right K temp. Ask Phil that about his zoanthids, if you change the color temp or PAR or other variables they will change their zooxanthalle to be more productive for the environmental conditions. (and some times look like crap to us)
Most all brown leathers can turn greenish and then back to brown. The real neon green leathers can go from bright green to brown and back. BUT a Brown leather can not go to bright neon green and stay that way. Get it ?