Problem with siunitx code after package update

Question

Consider the following MWE where the code comes from here and is then modified a bit:

\documentclass{article}
\usepackage{siunitx}
\ExplSyntaxOn
\NewDocumentCommand\SIexpr{O{,}mm}{
  \SIext:nnn{#1}{#2}{#3}
}
\cs_new_protected:Npn \SIext:nnn#1#2#3{
  \seq_set_split:Nnn \l_SIext_input_seq{#1}{#2}
  \seq_pop_left:NN \l_SIext_input_seq \l_SIext_first_tl
  \seq_clear:N \l_SIext_output_seq
  \seq_put_right:Nx \l_SIext_output_seq{
    \fp_compare:nTF{\l_SIext_first_tl > 0}
      {\num{\l_SIext_first_tl}}
      {-\num{\tl_tail:V \l_SIext_first_tl}}
  }
  \seq_map_inline:Nn \l_SIext_input_seq{
    \seq_put_right:Nx \l_SIext_output_seq{
      \fp_compare:nTF{##1 > 0}
        {+\num{##1}}
        {-\num{\tl_tail:n{##1}}}
    }
  }
\SI[
    parse-numbers = false,
    quotient-mode = fraction,
    input-product = *,
    output-product = \cdot
  ]{
    \sisetup{parse-numbers}
    \left(\seq_use:Nn \l_SIext_output_seq{}\right)
  }{#3}
}
\ExplSyntaxOff
\begin{document}
\SIexpr{5, -2*1}{\s}
\end{document}

Whan I compile via pdflatex using my up-to-date TeX Live 2021 distribuion, I get the following warning and error:

Package siunitx Warning: Option "quotient-mode" has been removed in this
(siunitx)                release.
! LaTeX3 Error: The key 'siunitx/input-product' is unknown and is being
(LaTeX3)        ignored.
For immediate help type H <return>.
 ...
l.41 \SIexpr{5, -2*1}{\s}

How do I fix the code in order for it to compile properly once again?