Hello,
did you find a solution for this?
I need to do exactly the same thing as I have a lot of repeater fields and flexible content which is blowing my database.. but I cannot find a solution.
My first Idea was to find empty fields and check for the saved value and unset it in $_POST[‘acf’] if it was empty before as well. But I had to abandon this because it did not save if somebody deleted a repeater field.
My second idea then was to get 2 arrays old and new and compare the values
but this is not working because one uses keys the other names and the structure is not the same 🙁