The first, quiz type, has a significant drawback: to answer the questions you needed to know some particular facts (for example, the diameter of some telescope, or the year of some Kopernic's publication). This is the most likely reason why the presentation type was replaced.
In 2018 National level Olympiad was held in Kyiv. Thus, the quasi-observational round could be conducted in a planetarium. Unfortunately, there are not planetariums in all cities of Ukraine. Thus, as in 2019 National Olympiad was held in Zhytomyr, there wasn't any possibility to conduct quasi-observational round in a planetarium. However, because of all the described drawbacks of the presentation type round, juries didn't want to return to it. So the round was conducted in the Stellarium app. Here
you can find tasks of quasi-observation rounds of the Olympiads of the past years. To get an idea of what you can expect in the planetarium round, you can look through the observation round questions of the Moscow Astronomy Olympiad
. Of course, this is far less effective than solving the tasks under the same "sky" in the same planetarium as participants did. However, this will give a good idea of what to be prepared for.