Seems like you have a mystery here that may need some detective work to solve. Has anything else changed about 3 weeks ago other than the change in food? What has the weather been doing? Hot and humid weather makes them eat less and lay less. Was it a sudden stop of laying or did the eggs taper off? Is there any chance a snake or other predator could be sneaking into the coop and stealing the eggs? We had that happen about a year ago - we might never have known if the snake hadn't stopped on the coop steps one day to digest the 3 eggs it had eaten.
If the only difference you can come up with is the food, the way to test if that's the cause of not laying is to add the pullet feed back in and see if they start laying again in a week or so. If no change and you still don't get any eggs, then the food is probably not the issue.
So if they do start laying again then the question is, why do they like the one food and not the other? Are they the same form or is one crumbles and the other pellets (for instance)? Are the ingredients similar? Did the pullet feed have an ingredient the layer doesn't have, or maybe the layer has an ingredient that they don't like? I would have thought the grower would have had more protein than the layer, but it doesn't seem so.