I do not understand why this generates a Underfull \hbox (badness 10000) warning:
\documentclass{article}
\usepackage{enumitem}
\usepackage{tabularray}
\UseTblrLibrary{varwidth}
\usepackage{xcolor}
\NewDocumentEnvironment{mytblr}{+b}{
\noindent\begin{tblr}{hlines, vlines, colspec={X[1]X[2]}, measure=vbox, row{1} = {gray8,font=\bfseries}, stretch=-1, rowsep=4pt, row{2-Z} = {font=\footnotesize}}
#1
\end{tblr}
}{}
\begin{document}
\begin{mytblr}
Case & Description \
A & B \
C & D \
\end{mytblr}
\end{document}
Thank you in advance!