monsters have different colors suddenly?

[Kinotan]

hi
i downloaded purebdcraft a few weeks ago. but something happened so i had to reinstall minecraft etc. today i redownloaded it and noticed that my creepers all have different colors now (all squids also, as far as i can see). this wasnt the case a few weeks ago. is this something new? is there some kind of a config file somewhere, where can i set up so there wont be different colors? (purepdcraft for 1.16 btw, Minecraft 1.16.5 java version on Windows.)

EDIT: uh my bad. i dont know how but I did not see the "bug" section. so i probably posted this in the wrong section.

[HanFox]

This is a feature of OptiFine. Creeper's (and other mobs) have different skins due to the Random Mobs part of OptiFine.

[Kinotan]

Oh I see, I found the feature now. If I remember correctly, I didnt have Optifine installed a few weeks ago. Thanks for explaining me!