Steps to Reproduce:
1. Go to this website and download and install the application from the website, and do necessary updates if it prompts you to. https://www.filecroco.com/download-universal-minecraft-editor/

2. Open Minecraft, and create a world in creative with cheats enabled and name the world "Test"
3 Exit the world
4. Go into Universal Minecraft Editor and click on open, after that, select the world "Test"

5. Go to Players: ~local_player and then go to the armor slot.

6. Expand the 2nd folder down in the Armor list and type in minecraft:banner for the name.

7. Save the world and exit Universal MC.

8. Go back into the world "Test," and resume gameplay as usual.
Observed Results:
The black banner that acts as a chestplate occasionally glitches, as shown in the photos below. The banner patterns don't matter.
Expected Results:

The black banner should remain just how the pillagers and vindicators wear banners.
(briefly describe what should happen)