Remember the old texture of Cassiopeia, which is pictured here on the left? I do. And I'm constantly reminded of it to this day, a whopping 3 years later, after her texture update in the Shurima event that launched Azir. These textures _STILL_ show up when Cassiopeia dies in almost every skin she currently has. She turns to stone, falls over, and the moment she strikes the ground and cracks, she reverts to this ancient texture. It's off putting, irritating, and it's been a graphical error for 3 years running now.
I get that you might not care a lot about Cassiopeia because she's not Ahri or Ezreal, but that's no excuse for this to remain as it is. This seems like it would require some of the simplest work to correct (just replacing the affected model with the new texture, in gray), and yet another year has passed and it's still a thing. Please fix it. Now that she's getting a new skin, it would be an utter shame if it was marred by this oversight, and our snake lady deserves better than this.
Edit: Thanks to Weathered below, here's a video of what happens: