Unfortunately, what I was using to generate the XP build was built into the version of Visual Studio I was using at the time. A few years ago, this was no longer supported, and though there are apparently workarounds, what's officially deprecated seems to be outright broken:
https://www.reddit.com/r/VisualStudio/comments/11wl8hb/has_anyone_tried_to_get_x...
The last version I made WinXP builds for was v1.0.2 (~2021 timeframe), which isn't linked on the site, but I keep all my past releases, and you can access it here:
www.shadowofthewyrm.org/releases/ShadowOfTheWyrm-WinXP-1.0.2.zip
If you're okay playing an older release, this might be a solution?