Always,
IIRC, they do not have Chanuka at all. Some had a version of Purim but some did not (perhaps because of fear of the Christian population) and their holier people fasted three days before Purim. They have a full Tanach in Ge’ez which is not Hebrew but is a semitic language. However, I believe that their Tanach is the same as the Old Testament used by Ethiopian Christians. And there was definitely a period where they were not allowed to have other, non-Christian approved, books.
They keep one day of Yom Tov. And count Shavuos from the last (7th) day of Pesach, not the first day of Pesach. So their Shavuos is on the 12 or 13 of Shevat. They celebrate it as both a harvest festival and Matan Torah.
I need to look up if they have haftorah or takanos Ezra.