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

pse-core
2025.6.1

This version was deleted from PyPI around 2025-12-04. Installing fails with:
$ pip3 install pse-core==2025.6.1 ERROR: Could not find a version that satisfies the requirement pse-core==2025.6.1