Not kosher for Passover matzah

What’s the Halacha regarding matzah marked “not for Passover “
I don’t understand why they don’t indicate more clearly that they are not kosher for Passover, same thing with matzah meals , etc… they look identical

Should not be eaten on pesach. It’s chametz.

Why brands don’t differentiate the design more is something you’ll need to ask the companies themselves. It’s a good question.