MarsSeed [1] filed a deletion request for mingw-w64-qt5-canvas3d [2]: Broken, unused, EOL.
Deprecated since 2018, removed from Qt 5.13 released in 2019. And now the source is unavailable from its original upstream URL. [1] https://aur.archlinux.org/account/MarsSeed/ [2] https://aur.archlinux.org/pkgbase/mingw-w64-qt5-canvas3d/
