MarsSeed [1] filed a deletion request for soapysdrplay [2]: SoapySDRPlay per se has been discontinued, repo and its release tarballs deleted (404).
Upstream only develops the successor, called SoapySDRPlay3. There's already a git package for it on AUR: https://aur.archlinux.org/packages/soapysdrplay3-git [1] https://aur.archlinux.org/account/MarsSeed/ [2] https://aur.archlinux.org/pkgbase/soapysdrplay/
