Scaling, not zooming

[Carsten Mattner <carstenmattner gmail com>]

When using 3.22.12 with GDK_BACKEND=wayland under Weston or Sway
compositors, for some reason windows/widgets are zoomed out when the
default size is bigger than the display at hand or even a random GTK3
file dialog somehow doesn't manage to snuggle into the physical
display size. This results in blurred out GTK windows that are hard to
use.

I have been unsuccessfully looking for the right gsettings key that
disables zooming and ideally re-enables widget scaling.

What's the key?