The Bug

All villager types define a body texture, except savanna zombie villagers. The non-zombie one seems like the mistake, as it looks identical to the plains body, but the plains one has a body of color differences.

Observed Result

A body texture was missing for the Savanna Zombie Villager

Expected Result

The Savanna Zombie Villager would have a body texture

Suggested Fix

Create a proper body texture, and apply it to both.