It looks like you have cornish cross chickens, the only kind that sometimes do need to have their feed limited. (Based on the way they look, and based on them laying down to eat when they were younger, before you started limiting their feed.)
They may have finally figured out what amount is right to eat. Or not.
You will probably just have to pay attention to how they act, and you may end up switching back and forth between free feed and limited feed, depending on how they are doing at what time.
For new chicks, if you get Rhode Island Reds, it should be fine to feed them as much feed as they want. Even if the store mis-labels the chicks, if they look red, they should be a kind that can handle free-choice feed.