You're looking at StableBuild's Deleted PyPI mirror - where we index all deleted packages from the Python package registry.

fdb5lib
5.17.4rc1

This version was deleted from PyPI around 2026-01-29. Installing fails with:
$ pip3 install fdb5lib==5.17.4rc1 ERROR: Could not find a version that satisfies the requirement fdb5lib==5.17.4rc1