\DocumentMetadata{
  uncompress,
  pdfversion = 2.0,
  testphase = {phase-III,table,math},
}
\input{regression-test}
\documentclass{article}
\usepackage{unicode-math}

\begin{document}
\ExplSyntaxOn
\luamml_set_filename:n {
    \jobname .mml
  }
\luamml_process:  
\luamml_begin_single_file:
\ExplSyntaxOff

$ \sqrt{x} $

$ \sqrt{\sqrt{x}} + 2 $

$ x = \sqrt{\sqrt[3]{y^2}} $

$\sqrt[3]{y}$
\end{document}