Why is KDE ignoring my overshadowing of a desktop entry?

(From SuperUser)

When I installed smplayer, it installed mpv along with it. This created a desktop entry pointing to mpv, which I don't want. I tried overshadowing it with a file in ~/.local/share/applications called mpv.desktop with these contents:

This doesn't work, and I can still search for and execute mpv from my application menu. I tried giving the overshadowing file a Type and even a Name to no avail. Why isn't the entry becoming hidden, and how can I hide it?

I am running Kubuntu 24.04.4 LTS.