I think that most, if not all spawn egg textures are INCORRECT, compared to the Java edition. The core of the problem seems to be that the layers of the spawn egg texture were blended together incorrectly. This is most obvious with the shulker spawn egg (it is a light lavender color in Java edition, but a dark purple color in MCPE), but it appears to exist for either all or most spawn eggs, if you compare the Java edition against MCPE closely enough. And annoyingly, the mistake has carried over into every single official texture pack, so the bug has to be fixed on those, too.

Steps to Reproduce:

1. Create a creative world in Java edition and grab some spawn eggs, especially the shulker & zombie horse spawn eggs.
2. Create a creative world in MCPE and grab the same spawn eggs.
3. Compare how the spawn eggs look in MCPE vs. Java edition.