So if I understood it right this change will only affect authors. Curators will loose nothing and even get more since the part take from the author is distributed as curation reward.

Sort of? It should help curators a little bit as people being discouraged from voting in the first fifteen minutes should lead to real curation distributions closer to the nominal 25%. But as @glenalbrethsen pointed out they have the opportunity to give the full 25% to curators instead of doing the rewards pool nonsense, and chose not to.

It also hurts readers and unsophisticated voters who will have to deal with efforts by authors to not get votes in the first fifteen minutes.