Unlike on <1.19 resourcepacks, negative space/zero-width unicodes fail to load when the font-file has any issues. Be that a texture missing etc. This only seems to affect zero-width unicodes as others load just fine.

As in the image, where player.png is missing, the zero-width is the rectangle, whilst the logo unicodes load just fine. Caused alot of confusion seemingly as this never was the case before 1.19.