You're looking at StableBuild's Deleted PyPI mirror - where we index all deleted packages from the Python package registry.
ensmallen was reported malicious
OSV:MAL-2026-5315 - Malicious code in ensmallen (PyPI)

ensmallen
0.7.0.dev7

This version was deleted from PyPI around 2026-06-08. Installing fails with:
$ pip3 install ensmallen==0.7.0.dev7 ERROR: Could not find a version that satisfies the requirement ensmallen==0.7.0.dev7