Trilby [1] filed a deletion request for qt5-webengine-widevine [2]:

This package is no longer necessary; qt5-webengine users can now use chromium-widevine{,-dev} for their widevine needs.

[1] https://aur.archlinux.org/account/Trilby/ [2] https://aur.archlinux.org/pkgbase/qt5-webengine-widevine/