/usr/share/perl5/LaTeXML/Post/ is in latexml 0.7.0-1.
This file is owned by root:root, with mode 0o755.
..
/usr/share/perl5/LaTeXML/Post/Collector.pm
/usr/share/perl5/LaTeXML/Post/CrossRef.pm
/usr/share/perl5/LaTeXML/Post/Graphics.pm
/usr/share/perl5/LaTeXML/Post/LaTeXImages.pm
/usr/share/perl5/LaTeXML/Post/MakeBibliography.pm
/usr/share/perl5/LaTeXML/Post/MakeIndex.pm
/usr/share/perl5/LaTeXML/Post/MathImages.pm
/usr/share/perl5/LaTeXML/Post/MathML.pm
/usr/share/perl5/LaTeXML/Post/OpenMath.pm
/usr/share/perl5/LaTeXML/Post/PictureImages.pm
/usr/share/perl5/LaTeXML/Post/PurgeXMath.pm
/usr/share/perl5/LaTeXML/Post/SVG.pm
/usr/share/perl5/LaTeXML/Post/Scan.pm
/usr/share/perl5/LaTeXML/Post/Split.pm
/usr/share/perl5/LaTeXML/Post/Writer.pm
/usr/share/perl5/LaTeXML/Post/XSLT.pm