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

passagemath-ecl
10.5.9

This version was deleted from PyPI around 2025-05-08. Installing fails with:
$ pip3 install passagemath-ecl==10.5.9 ERROR: Could not find a version that satisfies the requirement passagemath-ecl==10.5.9