Well... when it comes to productions like this, there's often several dozens of individuals involved. It's not possible to credit this to one, specific artist; the real world of the art industry doesn't work like that.
In some cases, each character has their own assigned rigging modelers, who are separate from texturing, concept art designers, storyboard artist(s), background designers, colorists, hair designers, etc. There's probably at least 10 artists involved with Izzy alone, before we even reach lighting, shading, special effects, and then you gotta consider all the sound input too, which is its own art, not to mention editors and clean-up artists.
There's literally an artist who's sole job is to angle and adjust the mane/tail as the riggers alter and move a character's head and body. In high quality 3D work, the riggers working on the face are a different team from those working on the body. They're not even the same people who animate accessories (like Sunny's saddlebag or Izzy's braclets); that's a different team of people.
All of these artists are then required to follow the direction, commands, and coordinate with the suggestions by art directors, animation and texturing supervisors, etc.
***So which artist would we even be specifying?***
Reasons like this we don't put `artist needed` tags on screencaps.
And you don't usually credit sources on leaked production material like this; it's not supposed to be available to the public.