FabioLolix [1] filed a deletion request for mkvtoolnix-qt5 [2]: Upstream removed Qt5 support in time for v0.82 released on 2024-01-02 https://mkvtoolnix.download/old_news.html, just use mkvtoolnix-gui from [Extra]
[1] https://aur.archlinux.org/account/FabioLolix/ [2] https://aur.archlinux.org/pkgbase/mkvtoolnix-qt5/
