Preventing Launch at Login
Turning off "Launch at login" in your preferences ( https://docs.tuple.app/article/34-preferences-general) should prevent Tuple from launching on log in. If you find that Tuple is continuing to launch, there may be something else on your machine launching the application.
Make sure that under System Preferences -> Users & Groups -> Login Items, Tuple doesn't exist in that list. Make sure that's true for all other users on that computer too (though only root users should make a difference, let's make very sure Tuple isn't getting started some place we don't expect!).
Check to see if Tuple is in the launchctl items. In terminal run:
launchctl list | grep -i tuple
You can then remove the Tuple launch item by running:
launchctl remove app.tuple.app-LaunchAtLoginHelper