Normal shulker box and purple shulker box have wrong color on maps

The Bug

Normal shulker box and purple shulker box have wrong color on maps (the two color should be interchanged).
Normal shulker box shows up as Color_Purple color on maps, the correct color should use either Terracotta_Purple or Terracotta_Magenta.
Purple shulker box shows up as Terracotta_Purple color on maps, the correct color should use Color_Purple.

How to reproduce

1. Summon some normal shulker boxes and some purple shulker boxes

   /fill ~3 ~ ~3 ~9 ~ ~9 minecraft:shulker_box
   /fill ~-3 ~ ~3 ~-9 ~ ~9 minecraft:purple_shulker_box
   

2. Obtain an empty map and use it
3. Take note as to what the color of the normal shulker boxes are displayed as, and what color the purple shulker boxes are displayed as
   → Normal shulker boxes and purple shulker boxes are displayed in the incorrect colors on maps

Expected Behavior

Normal shulker boxes and purple shulker boxes would not be displayed in the incorrect colors on maps. Instead, the colors of these two blocks on maps should be interchanged.

Code analysis

[Mod] Avoma has done a code analysis in this comment.