@timmse There was a new post here not just about clone fields but also flexible content. WIP: Managing ACF Flexible content and clone are broken with bricks theme active
A simple example for clone field is
Add an ACF field Repeater A
In A, add a Group B
In B, add a few fields you want.
Then add an ACF field Repeater C
In C, what you want is exactly the same as Group B. So instead of setting a new Group D and its subfields again, you can just use the Clone field and select Group B.
But in Bricks now, dynamic data from repeater C would not work, while it used to work according to others saying before.