The bug

When wearing a leather helmet that has a "pastel" sort of colour such as light pink, if the player looks in certain directions, the colour will completely disappear and just turn white. The exact colour code I used is #FFA6A6

I've tested this in 1.14 up to 20w22a and the issue still exists.

How to reproduce

1. Run the command

   /give @s minecraft:leather_helmet{display:{color:16754342}}
   

2. Put on the leather helmet
3. Press F5
4. Look up or down depending on which F5 perspective you are in
   → The leather helmet turns white

Check the video or images for a better explanation