normar creeper texture looks like a charged creeper but it is not charged

Last week I was playing Minecraft in my survival world normally when it started to get dark. As I was heading to my survival base, I saw that a group of creepers spawned with the appearance of charged creepers, which surprised me because they really looked like charged creepers. However, charged creepers do not spawn naturally. I completely ignored it thinking it would be a temporary bug, but it wasn't. I am not currently using any texture pack that changes the appearance of that mob; I only use the 'Fresh Animations' pack, and as far as I understand, it doesn't change the texture of the mobs directly. I hope you can help me! Thank you, Mojang Studios team!