If the screen resolution is 1600x900 and slightly lower, then the font of the NPC will be blurred with a probability of 50-50%, but if the screen resolution becomes square, then the font is fixed.

-The font becomes smooth, but not clear if it has a Russian font or an analog
-The font becomes clear if the screen resolution is higher than 1600x900 or it is square

-This bug has been around since version 1.16+

1. Enable Russian in the Minecraft Settings
2. Set the screen resolution to 1600x900
3. Enter the world (The font will break with a 50% probability)

Video: Demonstration of a font error