When using the package search bar at https://pypi-browser.org/ on my phone, the autocomplete functionality sometimes adds a space after the name I entered. For example: I start typing reques, I get a suggestion for requests, I tap it, and automatically a space is appended. But then when you submit, you go to https://pypi-browser.org/package/requests%20 (note the encoded trailing space) which fails with

Package 'requests ' does not exist on PyPI

you should strip leading and trailing white space before doing the query (or before submitting the form)