fc-scan creates patterns without styles
The last entry of fc-scan for https://github.com/IBM/plex/blob/master/IBM-Plex-Sans-Variable/fonts/complete/ttf/IBMPlexSansVar-Roman.ttf
does not have a style. That might be ok (the default for the font is Regular), but the same thing is done for https://github.com/IBM/plex/blob/master/IBM-Plex-Sans-Variable/fonts/complete/ttf/IBMPlexSansVar-Italic.ttf
And here it is definitely not ok, as it's an Italic font
fontconfig-2.13.92-3.fc32.x86_64
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