MarsSeed [1] filed a deletion request for python-specviz [2]: Upstream marked this as EOL 3 years ago, and pushed an empty package update as version 0.8 to PyPI.
The former functionality of specviz is offered by the maintained jdaviz tool. [a] [a]: https://github.com/spacetelescope/jdaviz [1] https://aur.archlinux.org/account/MarsSeed/ [2] https://aur.archlinux.org/pkgbase/python-specviz/
