Why is LaTeX printing an em-dash for the vertical bar (character 124)?

Question

I have lately seen a strange behaviour of my MikTeX installation and cannot explain it to myself. If I have the following code:

\documentclass{minimal}
\begin{document}
    |
    \char124
\end{document}

Instead of seeing the vertical bar twice, this is what PDFLaTeX gives me:

Translating the same code with LuaLaTeX works fine:

Any idea how to fix this and where to look? I see no

The log shows nothing strange from my point of view:

    This is pdfTeX, Version 3.141592653-2.6-1.40.24 (MiKTeX 22.3) (preloaded format=pdflatex 2023.4.19)  19 APR 2023 21:25
entering extended mode
 restricted \write18 enabled.
 %&-line parsing enabled.
**./TEST.tex
(TEST.tex
LaTeX2e <2021-11-15> patch level 1
L3 programming layer <2022-05-04>
(C:\Program Files\MiKTeX\tex/latex/base\minimal.cls
Document Class: minimal 2001/05/25 Standard LaTeX minimal class
) (C:\Program Files\MiKTeX\tex/latex/l3backend\l3backend-pdftex.def
File: l3backend-pdftex.def 2022-04-20 L3 backend support: PDF output (pdfTeX)
\l__color_backend_stack_int=\count185
\l__pdf_internal_box=\box50
) (TEST.aux)
\openout1 = `TEST.aux'.
LaTeX Font Info:    Checking defaults for OML/cmm/m/it on input line 3.
LaTeX Font Info:    ... okay on input line 3.
LaTeX Font Info:    Checking defaults for OMS/cmsy/m/n on input line 3.
LaTeX Font Info:    ... okay on input line 3.
LaTeX Font Info:    Checking defaults for OT1/cmr/m/n on input line 3.
LaTeX Font Info:    ... okay on input line 3.
LaTeX Font Info:    Checking defaults for T1/cmr/m/n on input line 3.
LaTeX Font Info:    ... okay on input line 3.
LaTeX Font Info:    Checking defaults for TS1/cmr/m/n on input line 3.
LaTeX Font Info:    ... okay on input line 3.
LaTeX Font Info:    Checking defaults for OMX/cmex/m/n on input line 3.
LaTeX Font Info:    ... okay on input line 3.
LaTeX Font Info:    Checking defaults for U/cmr/m/n on input line 3.
LaTeX Font Info:    ... okay on input line 3.
[1{C:/Users/MYUSERNAME/AppData/Local/MiKTeX/fonts/map/pdftex/pdftex.map}]
(TEST.aux) ) 
Here is how much of TeX's memory you used:
 236 strings out of 478599
 6311 string characters out of 2852479
 294171 words of memory out of 3000000
 18483 multiletter control sequences out of 15000+600000
 469259 words of font info for 28 fonts, out of 8000000 for 9000
 1141 hyphenation exceptions out of 8191
 33i,5n,35p,127b,92s stack positions out of 10000i,1000n,20000p,200000b,80000s
<C:/Program Files/MiKTeX/fonts/type1/public/amsfonts/cm/cmr10.pfb>
Output written on TEST.pdf (1 page, 9186 bytes).
PDF statistics:
 11 PDF objects out of 1000 (max. 8388607)
 0 named destinations out of 1000 (max. 500000)
 1 words of extra memory for PDF output out of 10000 (max. 10000000)