This is not correct.
With the previous system, APB (Admission Post-Bac), candidates ordered their wishes, and a bunch of (known, public) criteria were used to rank students in each of the curriculum they enter in their wishes. There criteria included, among other things and as the most important factor the position of the curriculum in the candidate ordered wishlist. So if a candidate placed a curriculum at the top of their wishlist, the particular curriculum will prefer this student over one who placed it in the third position for example.
Now, with the new system, Parcoursup, two main things changed.
The first thing: curriculum have to manually order candidates according to whatever criteria they want. Universities are given access to grades and high school of the candidates. This can lead to (sometimes unconscious) discrimination (candidate from a prestigious high school is more likely to get what they want compared to someone who went to a suburb high school, for example). This is already stupid. The fact is also that candidates do not know the criteria in advance, and that the criteria may differ (and trust me, they do!) depending on each university and curriculum. Grades now may be a part of the selection, but they do not have to. And there is no way to really know if they do and if so, how.
This is a nightmare for candidates (and their parents).
The second thing: candidates can no longer order their wishes. This is really, reaaaaaaally, plain stupid. And it is what can lead to deadlock as I explained in another comment. It is no longer possible to apply an optimal pairing algorithm such as stable marriage (Gale-Shapley, of which a variant was used by APB). So the professors managing each curriculum have to manually set the number of candidate they call in their ordered list. If your department has 100 places for new students, then you might call the top 200 of your candidate local ranking at first, knowing that some of them with strong application will also be called somewhere else (because they most likely have a strong application there too) and they might prefer to go there. Now what happens when you have say 70 confirmed wishes and you are left with 50 candidates waiting. If they are waiting, it's most likely because they would like another university better than yours, but they can't let your offer go as long as they are not sure that this other university offers them a place. And in this other university, the situation is the same, with other people who may prefer to go to your university. And there we have a deadlock. A completely stupid deadlock that would be avoidable trivially if candidates could simply order their wishes.
This leads to even more stress for candidates and their family because it often takes up month before the situation is little by little solved by candidate settling for their second or third choice while it would have been possible to make everyone more happy way more quickly.