The error:
$ pandoc --output test.pdf test.md
Error producing PDF.
! Argument of \HyPsd@@ReplaceFi has an extra }.
<inserted text>
\par
l.55 ...e{toc}{section}{\url{http://example.com/}}
The two-line input file test.md:
<http://example.com/> {-}
=========================
The version:
$ pandoc --version
pandoc 3.8
Features: +server +lua
Scripting engine: Lua 5.4
User data directory: XXX
Copyright (C) 2006-2025 John MacFarlane. Web: https://pandoc.org
This is free software; see the source for copying conditions. There is no
warranty, not even for merchantability or fitness for a particular purpose.
Comment: The same error appears using other heading syntaxes, e.g. -------- and ###.