When opening a new .deb file (which is a newer version), the Snap Store will prompt to remove the already installed software

This is wrong in my opinion. There should the a reinstall button (if the .deb file version == installed version), a upgrade button (if .deb file version > installed version) and the remove button (just as it is already presented). To be honest, it doesn't make much sense to me that if I open a newer version .deb file of a already installed program, the Remove button is presented. This button should only appear if I searched for the program on the Installed Software Listing.

Because of this oversight, I was forced to install the newer version .deb file using "sudo dpkg -i" so that I had the program up-do-date, which isn't friendly at all for newcomers.

This is a known limitation of the current implementation. Previously, it was not possible to remove already installed packages using GNOME Software (because they are not present in system AppStream metadata). There used to be an "Install" button always displayed for local packages, but it actually did not work if the package was already installed. So, an actual local package detection code that displays a "Remove" button if the local package is already installed was added, however the "Update" part code/button was not added because there was not enough capacity/time to properly implement this, see this comment from Matthias Clasen: https://gitlab.gnome.org/GNOME/gnome-software/-/issues/965#note_789500

As a workaround, you can click the "Remove" button to uninstall the old package, then re-open the new deb file and install it by clicking "Install".

I am aware that there is that workaround, but by the end of it all, I can't understand why there wasn't an implementation to compare the package version with the installed one, and then automatically run 'sudo dpkg -i *.deb' automatically, to perform the update. Even if the .deb file has an older version number, the Store could ask if the user wants to downgrade, and warn that issues could arise from doing that.

> There used to be an "Install" button always displayed for local packages, but it actually did not work if the package was already installed.

I don't think this is correct - I used to use the install button to install updates from a .deb for both VSCode and Discord (and a few others I've since forgotten). This workflow broke when I upgraded Ubuntu, with the newer Snap Store presenting a remove button instead.

This issue seems to still be present on 22.04 and 22.10, given that it never got fixed. I've had to help a few people in updating software that doesn't have an apt repository, and requests the user to download a .deb file (like Discord). They would have to uninstall the application and install it again with the newer .deb file, or update it using "sudo dpkg -i package_nage.deb". This has to be fixed soon, given that the user experience is poor in this sense.

Personnally I gave up on snap-store for my clients , replacing it with gnome-software , I suggest people to do the same until 24.04