When showing the grid it's easily visible that the wing is clearly over the tile on the right, and not at all on the left. This happens no matter where I place him.

I've included Albino Xeldron as comparison. It looks much better, as it only does have 1 pixel more on the left tile than on the right.

Tested on:

Windows 10 with Firefox 65.0.1 (64-bit)

Android 9 with Firefox 65.0.1

It looks like removing him and placing him again has worked. I didn't evolve him recently, but i believe that it was like that since around the time of his evolution.

@Sokyran

I updated the evolution script and I noticed that the house position was not updated while evolving a pet. This should be fixed now!