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

azureml-dataprep-rslex
2.16.0

This version was deleted from PyPI around 2025-07-19. Installing fails with:
$ pip3 install azureml-dataprep-rslex==2.16.0 ERROR: Could not find a version that satisfies the requirement azureml-dataprep-rslex==2.16.0