It is indeed https://github.com/Fuco1/org-timeline. I'm currently contributing to it, so I might as well fix this in the package. I was just looking for a quick fix, and for a clearer syntax in my items.
It isn't currently possible to disable this. I could potentially look at writing a time range within the same day in the shorter form, which would make sense. Could you provide a link to the org-timeline package - there was something called org-timeline as part of Org mode which was removed a few years ago, and I can also see https://github.com/Fuco1/org-timeline. I'm guessing the later but would be good to know for when I take a look at this.
Somehow it doesn't seem to do it consistently.
I created two items (in the same file) with that timestamp format, saved and synced after creating each item, and the one I created after got the new format after the first one.
Somehow the first one only got this change after a few syncs.
aizensoosuke
Beorg changes all of my timestamps with the format <2021-03-10 Wed 8:00-11:00> to the format <2021-03-10 Wed 08:00>--<2021-03-10 Wed 11:00> after a short amount of time.
This is a big problem for me because the org-timeline package on emacs doesn't support this format.
Is this a bug or is it a feature? Can I disable this?