The texture pack is incompatible, or broke it itself during the release of new updates.
You could have "layered" the texture packs incorrectly. One of the packs might have to be placed above, or below the other inside of the Resource Packs menu. This bug has happened to me a few times while applying packs for my Bedrock world, though this fix might not be the case for Java.
You have shaders, optifine, or some client mod installed that's interfering with your resource packs/ mods folder
From what I'm seeing in the image you attached, you have some shaders installed, and I'm only guessing that it could be to do with the last bullet. I could be entirely wrong, though.
I was using programers art and another texture pack to make Minecraft look old and this happened to the zombie villager
(just thought I should share)
NamePerson was_taken
There could a few reasons as to why this is:
From what I'm seeing in the image you attached, you have some shaders installed, and I'm only guessing that it could be to do with the last bullet. I could be entirely wrong, though.