$\pu{1.083780 mol}$
renders as $\pu{1.083780 mol}$
I think mhchem renders \pu.
It's because you have a tiny, invisible character between the 8 and the 0. Move your arrow keys back and forth inside the text; you'll find you need one extra key to traverse the gap between 8 and 0.
https://www.babelstone.co.uk/Unicode/whatisit.html says:
U+0024 : DOLLAR SIGN {milréis, escudo}
U+005C : REVERSE SOLIDUS {backslash}
U+0070 : LATIN SMALL LETTER P
U+0075 : LATIN SMALL LETTER U
U+007B : LEFT CURLY BRACKET {left brace}
U+0031 : DIGIT ONE
U+002E : FULL STOP {period, dot, decimal point}
U+0030 : DIGIT ZERO
U+0038 : DIGIT EIGHT
U+0033 : DIGIT THREE
U+0037 : DIGIT SEVEN
U+0038 : DIGIT EIGHT
U+202C : POP DIRECTIONAL FORMATTING [PDF]
U+0030 : DIGIT ZERO
U+0020 : SPACE [SP]
U+006D : LATIN SMALL LETTER M
U+006F : LATIN SMALL LETTER O
U+006C : LATIN SMALL LETTER L
U+007D : RIGHT CURLY BRACKET {right brace}
U+0024 : DOLLAR SIGN {milréis, escudo}
There is a U+202C
between 8
and 0
.
This special character is used to mark the end of a right-to-left script part in a left-to-right text (or vice versa).
U+202C : POP DIRECTIONAL FORMATTING [PDF]
at the end. That's one of the reasons I use web browser's console instead: F12
→ Console, put this on the sidebar and you got a nice built-in calculator with all JS functions at hand:)
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