Is there a way to set pages:false to the root of my site? My client keeps accidentally creating pages at root level instead of in their proper sub-folder.
You can do that in the site.php blueprint.
Oh my gosh, duh. I have never noticed that line in there.
does pages: false in the sites blueprint not work anymore in Kirby 4?
options:
pages: false
But the button is still there and does its thing.

There is no such option. You need to add sections to create subpages anyway, then make your settings within these sections