I recently fresh reinstalled Xubuntu 20.04lts on two of my pcs. Suddenly after a few weeks, i discovered a couple of differences between these pcs, were i did not alter anything. It seems that the Software store (gnome-software) looks like being different versions compared between both systems. one has a Source tab on the top right next to minimize, the other lacks that and has a gear for options there. (containing nothing special only software and updates, and two options for updating software) This source tab gives access to flatpak software, and a little extra sources. Also i cannot find this tab anywhere on the other pc in the gnome-software application. The other point is, that on this pc, which has extra sources for software like flatpak, the snap-store seems to be replaced for gnome-software. What means, that when i click the snap-store icon, it starts gnome-software. also i tried running it by terminal with snap-store, but the same result. i dont know what happened here. first of all, how can i get these flatpak resources also, with that source tab on the other pc (in gnome-software), and how do i ¨restore¨ the snap-store to working state. the other pc by the way does have a working snap-store. i have compared the ppas of both, and there are no differences, and nothing has been added.
From what I have read before - the Ubuntu Software is a snap application, it does not have integration with FlatPak.
So you may to decide removing it:
snap remove snap-store
and install deb-packaged GNOME Software with FlatPak and Snap plugins instead:
sudo apt-get install gnome-software gnome-software-plugin-flatpak gnome-software-plugin-snap