What a very long winded way of saying "sometimes people aren't the idyllic norms that society has deemed of certain roles".
I think the problem with something like this is that once the message has been telegraphed, there's not much to build on from that. Yes, Leda does not revel in the wonders of motherhood, and even hates certain aspects of it, but what does that say about her as a person? The movie seems daring enough to ask the question, but not follow through with any kind of character building or resolution for this societally controversial stance.
There are some nice turns of metaphor, mainly the fruit and the doll being "nice" on the outside but rotten to the core, which plays right into how Leda sees herself, and how the family on the beach have something sinister under the "perfect" exterior. These metaphors aren't enough to elevate the absolute slog that his movie becomes after the first hour.
Colman and Buckley really carry this movie, but the performances are hindered by the very limited scope of the script and screenplay. I also found some of the camera work, editing and scene compositions a little basic and clumsy, especially considering they had the beauty of the Greek coast to work with.
Watching this straight after Red Rocket, which shows you can portray off-piste characters with a level of empathy and truth, really was the worst case scenario for The Lost Daughter. I feel it has so much to say, but is too scared to say it and follow through with the consequence. Then again, I am a single male in the dying days of his 20's, so maybe I just didn't get the nuance on show here because I can never experience what these people are going through.
Poor showing, I'd probably only recommend this if you must watch all the movies up for award contention this year.