On Gnome Shell on Wayland `wl-copy` is automatically detected but using
it requires switching focus to the temporary invisible window it creates
as a workaround to the Wayland security feature that only the focused
application can interact with the clipboard. This does not happen when
`nvim` is run outside of `tmux`, so I can only assume that `tmux` is
seen to be the focused application, even though it's running inside
`kitty`, rather than `nvim` when running inside `tmux`.