Since 2 days my AnkiDroid displays a strange syncing behaviour: Every time when I promt it to sync, it does so for a lengthy time, always downloading 200 or 300 media and a few hundred MB. When it is down I make it sync again and the process repeats.
It is probably because the media synchronization wasn’t completed yet at the end of the last sync.
The process can take a very long time, multiple hours even, especially if there a lot of media to be downloaded to AnkiDroid.
In this reddit post one of AnkiDroid Maintainers suggests that
You may want to sync overnight until the media sync completes
You can temporarily disable media synchronization by going to AnkiDroid settings > General settings, then toggle ‘Fetch media on sync’