Strange line break with tabularray

[Virgil121]

This is based on this question: https://tex.stackexchange.com/questions/749756/strange-line-break-in-tabularrays-latest-version

Some tables seem to be broken when compiling with the latest version of tabularray with the varwidth library and microtype. This code:

\documentclass{article}
\usepackage{tabularray}
\UseTblrLibrary{varwidth}
\usepackage{microtype}

\begin{document}

\begin{tblr}{
    hlines,
    vlines,
    colspec={c},
}
hello ($hello$)
\end{tblr}

\begin{tblr}{
    hlines,
    vlines,
    colspec={ccc},
}
& $g_0 > 0$ & $g_0 < 0$ \\
$q > 1$ & AAAAAAAAAAAAA & AAAAAAAAAAAAA \\
$0 < q < 1$ & AAAAAAAAAAAAA & AAAAAAAAAAAAA \\
\end{tblr}
\end{document}

Compiles to this, using lualatex (and an updated miktex distribution):

Aside from disabling microtype or varwidth, either using the previous version of tabularray or changing the measure specification to hbox or vstore fixes the issue. As mentioned by a user in the original question, adding \let\MT@varwidth@setup\relax also works as a workaround.

[lvjr]

It is also reported at TeXackers/tabularray#616 . Basically tabularray uses varwidth to measure cell widths and use the widths to create some \vboxes for cells. And I am not sure it is a proper solution to \let\MT@varwidth@setup\relax.

[schlcht]

Just for reference, I'm copying this MWE by @lvjr from the inactive tabularray issue tracker. It shows that tabularray is not at fault, but that it's some bad interaction with varwidth and luatex which I'll have to analyse at a later point...

\documentclass{article}
\usepackage{varwidth}
\usepackage{microtype}
\begin{document}

\newcommand\mytext{H )}
\newlength\mylen
\settowidth\mylen{\begin{varwidth}{\textwidth}\mytext\end{varwidth}}
\setlength\parindent{0pt}

Default:
\fbox{\begin{minipage}{\mylen}\mytext\end{minipage}}
\fbox{\vbox{\hsize=\mylen\mytext}}

Raggedright:
\fbox{\begin{minipage}{\mylen}\raggedright\mytext\end{minipage}}
\fbox{\vbox{\hsize=\mylen\raggedright\mytext}}

\end{document}

[schlcht]

Turns out it's a luatex issue, which I've reported here. Let's see...