pandoc/test/command/5836.md

% pandoc -f markdown -t latex
\newcommand{\vara}{\alpha}
\newcommand{\varb}{b}
$\vara \varb$
^D
\newcommand{\vara}{\alpha}
\newcommand{\varb}{b}

\(\alpha b\)

% pandoc -f latex -t latex
\newcommand{\vara}{\alpha}
\newcommand{\varb}{b}
$\vara \varb$
^D
\(\alpha b\)