Please apologize if this issue has already been reported, but I could not find it.
In plasma (currently running 5.25.4), there is no way to distinguish applications installed from distribution repositories from applications installed via Flatpak (and I suppose Snap, but I did not try). This would be particularly useful when applications is installed from both sources.
STEPS TO REPRODUCE
1. Install a software from both distribution and Flatpak
2. Search for this software in the KDE menu OR
2. From Dolphin, right click on a file and choose "Open with…" OR
2. From Thunderbird, click on an attachment, select "Open with" and click on "Other"
Software is present two times, without any clear indication of which one is installed via Flatpak. When wanting to use a specific version, this means the user has no choice other than trial and error.
There should be a clear indication about which software has been installed via Flatpak and which has been installed from distribution repositories. Using LibreOffice as an example, it could be written "LibreOffice" and "LibreOffice (Flatpak)", has it is partially the case when using Cinnamon.
Linux/KDE Plasma: Debian Bookworm (current testing), Plasma 5.25.4
(available in About System)
KDE Plasma Version: 5.25.4
KDE Frameworks Version: 5.97.0
Qt Version: 5.15.4