Summary:

When minimizing Minecraft and re-entering (with incomplete restarting into the game), all banners become white in the inventory. To make flags common, just re-enter the world.

The error is minor, but sometimes such errors affect more serious ones.

Steps to reproduce:

1. Enter the world in full screen (f11/or in settings).
2. Minimize Minecraft.
3. Return to Minecraft.

Observed results:

All banners in inventory will turn white.

Expected results:

The banners do not change.

Image:

Video:

2021-02-20 15-47-60.mp4