latex error with /testcases/block/04_header/with_auto_ids.text

[boutil]

Hi,

With a very recent version of latex, I see a test failure with the testcase block/04_header/with_auto_ids.text. The latex file produced is

\documentclass{scrartcl}

\usepackage[utf8x]{inputenc}

\usepackage[T1]{fontenc}
\usepackage{listings}

\usepackage{hyperref}

\setcounter{footnote}{0}

\hypersetup{colorlinks=true,urlcolor=blue}

\begin{document}
\section*{This is a header}

\subsection*{12. Another one-1-here}

\subsubsection*{Do \^{}\& it now}

\section*{Hallo}

\subsection*{Not now}

\section*{Hallo}

\section*{23232}

\section*{33333}

\subsection*{hallO}

\section{Header without ID}\hypertarget{}{}\label{}

\section*{Transliterated: Đây-là-ví-dụ}

\end{document}

which seems correct. When compiled with pdflatex 3.141592653-2.6-1.40.24 (TeX Live 2022/Debian), I get the following error

[...]
! LaTeX Error: Unicode character ụ (U+1EE5)
               not set up for use with LaTeX.

See the LaTeX manual or LaTeX Companion for explanation.
Type  H <return>  for immediate help.

There were no issue with versions of latex from Texlive 2021 and earlier. Let me know if you need more information.

[boutil]

Something which is certainly relevant to the issue at hand: the log says

(/usr/share/texlive/texmf-dist/tex/latex/ucs/utf8x.def
  File: utf8x.def 2022/08/07 UCS: Input encoding UTF-8

  Package ucs Info: utf8x disabled, assuming standard utf8 processing
  (ucs)             load ucs package to force utf8x processing.

apparently, since August of this year, utf8x falls back to standard utf8 inputenc, which might be the reason for the change of behaviour.