How to reproduce

1. Download the resource pack below and use it
2. Type out the character 帀 and press enter
   → See instead of having a star in a box symbol, you instead get a square box

This is probably caused by the game trying to map the characters onto the 512×512 map as 16×16 instead of 32×32 characters, causing the characters to be cut off, and rendered improperly.

(The resource pack replaces that character with a star in a box)