\documentclass{article}
\usepackage{tabularray}
\UseTblrLibrary{booktabs}
\begin{document}
\section{All good here}
\begin{tblr}{lccr}
\hline
Alpha & Beta & Gamma & Delta \\
\hline
Epsilon & Zeta & Eta & Theta \\
\hline
Iota & Kappa & Lambda & Mu \\
\hline
\end{tblr}
\section{Pb here}
\begin{tblr}{lccr}
\hline
Alpha & Beta & Gamma & Delta \tabularnewline
\hline
Epsilon & Zeta & Eta & Theta \tabularnewline
\hline
Iota & Kappa & Lambda & Mu \tabularnewline
\hline
\end{tblr}
\end{document}