Ironically, the deprecated [ﬁ] “LATIN SMALL LIGATURE FI” is less of a ligature in some fonts than ASCII f+i. It isn't required to be stylistically merged fi (connected or dotless etc), just be f+i in a single glyph, for legacy support.
that's from the top unicode expert https://twitter.com/FakeUnicode . Over the past 4 years i've learned a lot esoteric tech details about unicode from him.
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