Why is Machoke‘s post-trade max CP lower when it’s currently 100%?

I was swapping Pokemon with a fellow trainer, and I ran into something interesting that I could not find an explanation too.

While searching through my list, I saw I had a Machoke favorited. I clicked it and then checked its IVs. It was a 100%, and was about to back out and select something the different. Before backing out, I noticed the Machoke’s maximum post-trade CP was less than its current CP.

When trading, the IV ranges are re-rolled with a minimum IV range based on various factors and max IV range of 15/15/15. I would have expected the max post-trade CP to be equal to its current CP. I check a few other 100%s, and this was not the case

What’s different about this Machoke that would cause the maximum CP to be different while at 100%?