This change is great - although I have one major beef with it.
It isn’t obvious enough when you are editing that these breakpoints are selected. Therefore it’s easy to accidentally switch to these breakpoints and you can go about editing without knowing and all your changes are only on one screen size, causing you to have to redo all your changes over again.
My proposal: Have a giant warning alert when editing in these larger breakpoints.
This has happened to me more than once to be a slip-up on my part. This is truly terrible UX based on the amount of frustration this causes.