[BUG] Recurring tasks not compatible with Nextcloud Tasks

[provokateurin]

Describe the bug

Recurring tasks are seemingly not synced, because I also have to mark them as done in the Nextcloud Tasks web app.
I'm pretty sure the syncing itself is working, but the problem is that Nextcloud Tasks implements recurring Tasks differently.

To Reproduce

1. Create a daily recurring task in Nextcloud Tasks
2. Mark it as done in jtxBoard
3. See it is still not marked done in Nextcloud Tasks

Switching what is done in which app leads to the same result.

Expected behavior

The task should also be marked as done in Nextcloud Tasks.

[provokateurin]

I filed the same issue in Nextcloud Tasks, because I'm not sure which one is broken and needs fixing: nextcloud/tasks#3205