Relates to/clones part of MCL-10994.
The Bug:
In the Minecraft Launcher, the play button on the main screen as well as the summer announcement do not support some glyphs for the text written on it. As a result, it looks aesthetically poor.
In languages like Vietnamese, a workaround was to set the font entirely to default on the play button as a result of MCL-10994. However, this tweak didn't happen in the newer summer announcement. In English (Upside Down) it does not take place at all.
Observed Behavior:
The font only partially supports languages and inconsistently displays supported characters in either the normal font or the fallback default font, depending on the selected language.
Expected Behavior:
The font supports the language either completely or not at all. If not, everything should be set to the fallback default font; but not mixed.
Can confirm.