Datatool and Tabularray: "Misplaced alignment tab character &."

Question

I'd like to use datatool to populate a longtblr table (defined by tabularray) with data.

I expected this:

\documentclass{article}
\begin{filecontents}[overwrite]{data.csv}
Key,Value
a1,a2
b1,b2
\end{filecontents}
\usepackage{datatool}
    \DTLloaddb{data}{data.csv}
\usepackage{tabularray}
    \UseTblrLibrary{functional}
\begin{document}
\begin{longtblr}[evaluate=\DTLforeach]{colspec = {cc}}
\DTLforeach*{data}{
    \key=Key,
    \value=Value%
}{
    \key &
    \value\\
}


\end{longtblr}
\end{document}

to yield a table like:

but I receive the error:

27: Misplaced alignment tab character &.

Line 27 refers to: \end{longtblr}.

I added [evaluate=\DTLforeach] on a hunch based on the comments on this question. Deleting all the whitespace within longtblr has no effect.

MWE Using tabular

This yields the expected result:

\documentclass{article}
\begin{filecontents}[overwrite]{data.csv}
Key,Value
a1,a2
b1,b2
\end{filecontents}
\usepackage{datatool}
    \DTLloaddb{data}{data.csv}
\begin{document}
\begin{tabular}{cc}
\DTLforeach*{data}{
    \key=Key,
    \value=Value%
}{
    \key &
    \value\\
}


\end{tabular}
\end{document}

MWE Using xltabular

As does this:

\documentclass{article}
\begin{filecontents}[overwrite]{data.csv}
Key,Value
a1,a2
b1,b2
\end{filecontents}
\usepackage{datatool}
    \DTLloaddb{data}{data.csv}
\usepackage{xltabular}
\begin{document}
\begin{xltabular}{\textwidth}{cc}
\DTLforeach*{data}{
    \key=Key,
    \value=Value%
}{
    \key &
    \value\\
}


\end{xltabular}
\end{document}

But I'd like to make use of tabularray's rich feature set.