You can see several faint lines crisscrossing the textures for the Shadow Creatures that appear to be "seams" of some sorts and I'm not sure if this is across all platforms or the result of the translation of OpenGL/x86_64 code into Metal/arm64 instructions for macOS.
It looks like they're stitched together from several constituent parts with the lines being the "joints" to form a "mesh" of sorts that makes these entities easier to animate.