When running on Java 20, the timestamp has a weird character in it. This seems to occur on all recent versions of the game, at least back to 1.18.2. It does not occur when running on Java 19, 18, or 17.

(Current) Code Analysis:

ICU 72 changed date formatting to use Narrow-No Break Spaces (NNBSP), however the Minecraft text renderer does not consider this a space and renders the text NNBSP instead of a space, even though they should visually be the same. There is no easy fix outside either replacing all NNBSP with spaces or allowing NNBSP to be rendered properly.