Doing your own experiment is a good idea.
There are really two questions that have been debated at great length.
The first question, is anything actually wrong with the feed? So far, there are reports of chickens that do lay better on different feeds, and reports of other chickens that resume laying without having their feed changed. I have not yet heard of any results from having feed analyzed in a lab (although of course a lab would only look for certain things, and may not find other problems they are not looking for. As an example, testing protein will not detect problems in mineral levels, and testing for a certain toxin would miss a
Mine are quite old enough to lay and haven't layed either. I've had them since October. It's summer here and no eggs in sight. I don't feed them much food, they are mostly free ranged.
different toxin. So lab results may or may not be helpful.)
The second question, if something is wrong, who caused it and why? This second one seems to cause the most arguments, with people on each side accusing the others of ignoring the obvious explanation (along with comments that are much less polite.) Theories vary widely: manufacturing errors, cost-cutting by using cheaper ingredients, deliberate changes to make backyard flocks not lay eggs, etc. (Who benefits if backyard flocks quit laying? There are several proposed answers to that too. Again, arguments ensue.)
Currently, I'm curious about the first question, whether there actually is anything wrong with the feed. So I'm paying attention to who changed feed, and what the results were. If the hens lay better on new feed, I am also watching who tests again by changing back (very few reports on that style of test so far.) If the feed really is the only factor affecting the egg laying, it should be possible to switch back and forth and have the eggs start and stop. But if the egg laying is actually affected by something else, the feed may be able to switch back and forth without causing changes in the laying.