Closing and reopening partially loaded image leads to multiple parallel downloads

Jerboa Version

0.0.87-fdroid

Android Version + Phone

LineageOS 23.2 (Android 16), Pixel 4a

Describe The Bug

When opening images on a slow connection or from a slow instance, the download progress bar on the top slowly fills. When I go back before the image fully loads and open the image again, the progress bar now jumps between the previous progress and the new one, both slowly going forward.
It looks like the image is now being downloaded two times in parallel. This can be stacked multiple times.

See also this screencast

https://github.com/user-attachments/assets/30bc55d2-5682-4aa5-a0b4-2b169823599e

To Reproduce

1. Open image over slow connection.
2. Let it load a bit, e.g. halfway
3. Press back
4. Open the image again
5. The progress bar now jumps between two states
6. Repeat at step 2 to add more states.

In the case of a crash or when relevant include the logs

Apart from log entries like these, there is no debug log regarding image downloads

06-28 07:13:58.814 20264 20264 D jerboa  : got to community screen
06-28 07:14:37.710 20264 20264 D jerboa  : got to community screen

Reproduce the issue in Jerboa 0.0.87 on Android by reopening a partially loaded image over a slow connection and confirming that progress states accumulate. Trace the image-loading lifecycle across back navigation and reopening; done when reopening no longer leaves parallel downloads or competing progress updates, and the reproduction steps pass without regressions.