On my system I've manually updated the Noto Emoji font to get emoji 14 support because I'm not updating to Ubuntu 22.04 on my daily driver to get the new font support.
Emoji are often rendered using the system's font fallback mechanism. When one font doesn't have the glyph required, another font that does have the glyph gets picked. Most fonts don't have glyphs for non-western scripts; there are only a few fonts out there that cover most of the Unicode standard, often made up of several fonts combined.
You're not manually changing the font-face mid sentence, but when you use emoji the renderer is definitely switching fonts to one you didn't specify.
Emoji are often rendered using the system's font fallback mechanism. When one font doesn't have the glyph required, another font that does have the glyph gets picked. Most fonts don't have glyphs for non-western scripts; there are only a few fonts out there that cover most of the Unicode standard, often made up of several fonts combined.
You're not manually changing the font-face mid sentence, but when you use emoji the renderer is definitely switching fonts to one you didn't specify.