I've spent some time looking at this over the holiday break and I think this was caused by 1090203[0] which was fixed in cl-named-readtables/20230828.git455fbaa-2. I've verified that pgloader/3.6.10-4 builds successfully with sbuild and Salsa CI.
Regards, --Bradford [0]: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1090203
