[Bug]: Download progress bar and download size numbers are not in sync

[jeanas]

Checklist

• I agree to follow the Code of Conduct that this project adheres to.
• I have searched the issue tracker for a bug that matches the one I want to file, without success.
• If this is an issue with a particular app, I have tried filing it in the appropriate issue tracker for the app (e.g. under https://github.com/flathub/) and determined that it is an issue with Flatpak itself.
• This issue is not a report of a security vulnerability (see here if you need to report a security issue).

Flatpak version

1.15.4

What Linux distribution are you using?

Fedora Linux

Linux distribution version

Fedora 38

What architecture are you using?

x86_64

How to reproduce

1. Upgrade installed Flatpak apps from the terminal.

Expected Behavior

The progress bar that displays at the bottom displays the same percentage as the one I could compute by dividing the displayed downloaded size by the displayed total size to download.

Actual Behavior

This doesn't look right:

560 KB is very far from 0.17 * 140 MB ≈ 24 MB.

I have also observed the progress bar going back from 99% to ~90%, which is very weird to see.

Additional Information

No response

[jeanas]

I see that there was already a similar problem in #3448, but apparently it was fixed back then.

[canadaduane]

I wonder if this is possibly related--after a flatpak update --user, the numbers on the left of each / in the Download column do not seem to match the numbers to the right of each /, which is what I would expect if each flatpak has finished downloading:

[ExperimentalCyborg]

I just noticed this as well. Harmless bug but bad for optics - what else is messy/broken?