So, a thing I don’t see most people talk is that Trixie had a slight redesign in season 6 - since her first apperance Trixie always had a longer horn than a standard mare, one white shine in her eye instead of two, and highlights (the little triangular things that most mares have on their irises).
And in No Second Prances she still has those features. But in To Where and Back Again she has a standard horn, standard number of shines, and the highlights have been added. She also went from having a unique eye design to sharing one with Applejack (by that I mean the way her eye is drawn and the number of eyelashes she has, not the color of the eyes.)
Then, some time later on, in the following episodes they keep the AJ eye shape and the horn, but ditch the highlights. It’s just interesting how they alter Trixie’s design throughout the show in small ways.