PieFed.zip has no 404 page configured
This is actually intentional on the part of PieFed. We have the 404 page be as computationally cheap to serve as physically possible. This is a way to help spare the server from some kinds of scraping that have hit the fediverse in the past.
As for the redirect, I can take a look at it. I have reworked a lot of the redirects in the codebase to make more sense, but from time to time a new case I missed pops up. Thanks for the report.