In my Ubuntu 20.04, after I execute sudo apt replace && sudo apt improve, apt informs me that the package deal xdg-desktop-portal-gtk can’t be up to date.
As a consequence, if I strive sudo apt reinstall xdg-desktop-portal-gtk I get the message (in italian, however you may wasily think about what it means):

xdg-desktop-portal-gtk : Dipende: libgnome-desktop-3-18 (>= 3.17.92) ma non è installabile

If I run sudo apt listing -ua I get:

xdg-desktop-portal-gtk/eoan 1.7.1-flatpak1~eoan amd64 [aggiornabile da: 1.6.0-1build1]
xdg-desktop-portal-gtk/focal,now 1.6.0-1build1 amd64 [installato, aggiornabile a: 1.7.1-flatpak1~eoan]

Whereas the output of apt-cache coverage xdg-desktop-portal-gtk is:

  Installato: 1.6.0-1build1
  Candidato:  1.7.1-flatpak1~eoan
  Tabella versione:
     1.7.1-flatpak1~eoan 500
        500 http://ppa.launchpad.web/alexlarsson/flatpak/ubuntu eoan/principal amd64 Packages
 *** 1.6.0-1build1 500
        500 http://it.archive.ubuntu.com/ubuntu focal/principal amd64 Packages
        100 /var/lib/dpkg/standing

Flatpak is put in from its official PPA.

How can I remedy the battle? Is there an opportunity to “block” one repository for this particular package deal with the intention to get it from the opposite one? If sure, which is the model that I ought to choose? Thanks prematurely