There’s a new KWin effect called “Hide Cursor” (off by default for now, but try it!) that will automatically hide the pointer after a period of inactivity (Jin Liu, Plasma 6.1)

First item on the first TWiK after the 6.0 release and I already want 6.1, goshdarnit.

I was using unclutter on X11, but that understandably doesn't work on Wayland.

And looking at the code, they've included a hide-on-typing option, which might make it work better for me.
unclutter would always close tooltips and hover-menus on me, but I also didn't want to set a higher timeout, because then the mouse cursor would annoy me while typing...