Package updates in repository?

Hi Trisquel users!
I was wondering on what basis packages in our repository get updated. I discovered that my version of "digikam" (the photo management tool) is the one from 2020 and Synaptic Package Manager tells me that this is the latest version available.
Now my question is: How and when do packages get updated in the repository? Why is the latest version not available?

Cheers,
Hein