tabular p column type cannot become a table header

[teepeemm]

In

% !TEX program = LuaLaTeX
\DocumentMetadata{lang=en,testphase=latest,
  pdfversion=2.0,pdfstandard=ua-2,
}
\documentclass{article}
\title{Title}
\begin{document}
\tagpdfsetup{table/header-columns={1}}
\begin{tabular}{
	%c
	p{.22\linewidth}
	c
}
	header & data
\end{tabular}
\end{document}

the header becomes a TD. If I change the column type to c, then the header is the expected TH.