This extension disables the “Window Is Ready” notification.
mkdir -p ~/.local/share/gnome-shell/extensions/noannoyance@sindex.com
wget -O - https://github.com/sindex/no-annoyance/archive/refs/heads/master.tar.gz | tar --exclude=".*" -xz --strip-components=1 -C ~/.local/share/gnome-shell/extensions/noannoyance@sindex.com
Sadly, the only reliable way to load an extension is to restart the shell or worse still, the session when running under Wayland.
Enable or disable the extension:
gnome-extensions enable noannoyance@sindex.com
gnome-extensions disable noannoyance@sindex.com
NoAnnoyance is distributed under the terms of the GNU General Public License, version 2 or later. See the LICENSE file for details.