Export Latin Modern Math Greek: spurious spacing on Windows

Bug introduced in 12.0.0 or earlier on Windows

[CASE:4549185]

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To get simple LaTeX Greek in my figures, I am using U+1D6FC MATHEMATICAL ITALIC SMALL ALPHA to U+1D714 MATHEMATICAL ITALIC SMALL OMEGA in the font "Latin Modern Math" (see "Symbols defined by unicode-math").

But the output is different on the two machines I am using:

• 12.0.1 for Linux ARM (32-bit)
• 12.0.0 for Microsoft Windows (64-bit)

styledGreek = Framed @ Column @ {
  $Version,
  Style[
    CharacterRange[16^^1D6FC, 16^^1D714],
    FontFamily -> "Latin Modern Math",
    FontSize -> 24
  ]
}

Export[ToLowerCase[$SystemID] <> ".png", styledGreek]
Export[ToLowerCase[$SystemID] <> ".pdf", styledGreek]

Linux PNG (OK)

Linux PDF (OK)

Windows PNG (spurious vertical spacing)

Windows PDF (spurious vertical and horizontal spacing)

What is going on here?

I have checked the OTFs installed on the two machines (latinmodern-math.otf from GUST) and they are identical (SHA256: 6075562b771f8b82f0c179e363389684f2dd09de30038269e2628e504bd7be0f).

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NOTES:

• I already know about MaTeX.
• Related: Szabolcs on Greek.