Health Bar color expanding past border - how to fix?

I’ve had this weird issue where the health bar color expands past the border of the nameplate. It only happens on one character; all others are fine. I’ve normally just used a nameplate addon to get around the issue. This has now gone on for quite a while. I’m guessing I originally encountered it early in WotLK Classic, maybe even in TBC Classic.

I’ve now tried renaming WTF/Interface folders to remove any addon weirdness, but it had no effect.

Anyone know how to reset the functionality to the default behavior?

Picture:
https://i.imgur.com/sVRDV2q.png

Everything about that looks wrong. It definitely looks like you have a WeakAura or Addon messing with things.

If resetting the UI doesn’t work then next step is resetting all your CVars–this cannot be reversed.

/console cvar_default