Crosslink:
In the above thread, we are discussing just that: That it would be better if the software store defaults to .deb packages.
I will include a link to your post there for the ZorinGroup to reference your situation as a clear and excellent example.
I do not use the Software Store; I do all my installs and removal from terminal. Once I learned it, I began preferring the terminal by far to the GUI apps, even if I resisted it at first.
But - you can easily resolve the Snap or Flatpak confusion if you are not using them by removing them - or by removing their plugins from the Software Store.
If you are not using snaps or Flatpaks at all, you can just remove them:
sudo apt remove --purge snapd flatpak
If you are using snap or flatpak packages but do not want the Software Store showing their packages, you can remove the plugin for Software without removing or affecting anything else:
sudo apt remove --purge gnome-software-plugin-flatpak gnome-software-plugin-snap
You can also just remove One Plugin like gnome-software-plugin-flatpak and leave Snap or the other way around.