The bug

Discovered this while updating my resource pack to 1.21.2. The "color_when_undyed" parameter inside of the armor model file allows for the default color of a dyeable equipment item to be changed via a resource pack. However, this only affects the appearance when equipped; the item form will still use the old color.

How to reproduce

A resource pack comprised of modified assets from my own personal resource pack is attached.

1. Equip leather armor
2. Compare the item forms to the equipped forms

Expected results

They would be the same colour.

Actual results

They are not.

How to fix

Either make the item forms follow the color_when_undyed specified in the equipment model, or make the hardcoded color applied to the item customizable on its own inside of the item model file in an equivalent way.