I definitely saw threads from people asking about why they would be gaining much later on this plan…but the veterans always said hold your ground. But it is more unique cause it isn’t a general thing happening to most carns.
I think it isn’t the gain so much…….I think your focus is on WHY you appetite has increased so much that you are gaining.
The gain is the result of the increased appetite.
One thing comes to mind is your body needs it right now. Needs more something. Fat is the biggie that is coming to mind for me.
What I would do…and this is just me and what my thoughts would be to change it around a bit… so it is a personal thing I would do here :)…….I would try eating very fatty meats. If I geared toward leaner cuts I would add good fat but for a few days eat the ribeye fatty type meats. Hold the good fatty beef cuts. Get in a lot of that good fat and see if it changes anything.
Kinda like that focus on one thing time. Cut out all the other stuff you eat and pick beef. Nice cuts of fatty good beef. -----could make a huge difference ya know. I think it is one of those things where you go little by little to make a discovery 
One thing I sure know about me. When I gear toward chicken, leaner cuts of beef, or tend to graze a bit, like some sausage, tuna, bacon and eggs, and those less dense meats…I tend to get a heck of a lot hungrier. And thing is I don’t even realize I am doing it. I just eat what I want when I want. I then think, wow I am really starving here and my appetite increases and I wake up and think. Oops…I am out of good fatty beef and good fat and balance here.
So fat would be my main focus. I would increase the heck out of good fat.
Second would be make sure you aren’t cutting salt a bit and not realizing it and make sure you are drinking good water…just cause those 2 if are low in your body can easily drive hunger…but I am sure you know that 
So that is just a chat about it all and maybe some of that might help you and just take what you need from my info and throw out the rest LOL
Sometimes our bodies want that fat. Point blank. So I would be very aware of my fat content in a day. Very focused on it and make sure one day I increased that fat big time and see if it holds my appetite to a better situation.
Then I would just try that for a few days and re-evaluate.
This is interesting to me. I hope whatever peaked your appetite will be discovered in a way.