Created attachment 116013 [details]
Size of updates: Discover v/s "$ flatpak update"

SUMMARY
Flatpak backend of Discover does not differentiate between the installation size and the update size of the Flatpak packages (installation size always shown).

For example, in the attached image, the "io.atom.Atom" package update is 35.3MB, but Discover shows that the update is 133.3MB. This is most noticeable in the Flatpak Runtime updates, where Discover shows updates of more than 700MB, when sometimes the download does not exceed 30MB.

This may be a problem for users who have an Internet connection with a traffic limit (mobile connections), since some users may refrain from updating their system when they see the big size of the updates in Discover, in Flatpak packages.

STEPS TO REPRODUCE
When there is an update of some Flatpak package, run "$ flatpak update" and compare the size of the update with the one that shows Discover.

OBSERVED RESULT
In the updates, Discover shows the installation size of the Flatpak packages, not the update size. The user is informed of an incorrect update download size (much bigger than the real one)

EXPECTED RESULT
Discover shows the real size to download in Flatpak package updates.

SOFTWARE VERSIONS
Discover: 5.14.2
KDE Plasma Version: 5.14.2
KDE Frameworks Version: 5.51.0
Qt Version: 5.11.2
Operating System: KDE Neon 5.14, Ubuntu 18.04

ADDITIONAL INFORMATION
n/a