Is there any way to disable the focus-stealing behavior in GNOME whenever an app is launched? I have already tried changing the dconf value "focus-new-windows", but that doesn't make any difference, because I am not worried about apps that I launch from the terminal, but rather the auto-started programs (that take a minute or so to load at start-up and each time they steal the focus).
You can select your startup application in tweak tool just install by following command:
$ sudo add-apt-repository universe
$ sudo apt install gnome-tweak-tool
you should see a application called tweaks or you can run it by :
then you can change or remove the application which auto-start on boot