Reproduce:
-Install Optifine Forge (didn't test with Optifabric, Rubidium, Iris ect. the latter works in theory)
-Install any shader and turn it on while having inWorld healthbars
Result:
-inWorld healthbards will render white

First picture was taken with Optifine using internal shaders.
Second one is with shaders turned on.

I've seen a closed issue about this, however it looks like it was closed by the guy who opened it not long after without any result or developer inspection.
I know OF is hard to work with, however I've seen mods with similar features working fine with OF shaders, like Neat, Epic Fight, Name Pain and Find my friens so I though it might be possible to fix.

I also encountered this problem when using oculus, which affects the game experience a bit