Comment # 5 on bug 1226112 from Björn Bidar

(In reply to Fabian Vogt from comment #4)
> (In reply to Björn Bidar from comment #3)
> > What is left that kmozillahelper does that the new switch to use the
> > XDG-Portal doesn't do?
> 
> Nothing really relevant anymore FWICT.
> 
> > From my point of view there should be no downside to use portals by default
> > even outside of Plasma as it can useful for other use cases.
> 
> Not sure whether there are any edgecases. Some DEs might not have portals
> configured correctly or not available at all. So IMO doing this only for
> Plasma for now is safer.

I don't think that's needed since GTK will use the dialog that doesn't use
portals as fallback if no portal can be found:
https://gitlab.gnome.org/GNOME/gtk/-/blob/gtk-3-24/gtk/gtkfilechoosernative.c?ref_type=heads#L768