Sometime in Shadowlands when they changed the customization to segregate beards from mustaches, the “underlayer” texture that’d help “fill” out the beard was removed from almost every race.
It’s very apparent in Pandaren - see this example (and more in the tweet linked at the bottom). https://imgur.com/V4pS69I
In this Pandaren example, you wouldn’t have been able to tell they’re just scatter-shot flat textures because underneath would be the same color as the beard. Due to the lack of underlayer, beards lost a lot of the texture work that’d camouflage the imperfections.
It wasn’t exclusively targeted towards just facial hair or Pandaren, though. Here’s an example of it on a human: https://imgur.com/wbdnuEh
Same facial hair in both, it’s just one doesn’t have the underlayer texture of black hair on the skin which helps hide the rounded out portions of the 3D asset.
There’s never been communication on if this was intentional or not, so I wanted to post on it here. Some of the beards in the game now just look worse than they did before and it’s a real shame it’s lasted over an expansion now.
Thanks to DaveofCanada on twitter for most of the information & examples, inspired from his tweet and a conversation I had with him on it. https://twitter.com/DaveofCanada/status/1611083273391726598