There aren’t a lot of words I can add to these, as the pictures pretty much say it all. No this is not a result of cleaning gone bad either. Several neighbors have noticed the same thing, and many have already replaced their microwave along with other appliances and countertops.
Here is the inside of my microwave:
Here is the manufacturer’s picture of the inside of the microwave. Mine is next to it. See the difference?
Lennar has indicated that all the metal corrosion and discoloration is the result of lime buildup as indicated in my extensive Lennar construction issues spreadsheet. A more likely explanation is environmental concerns along indoor air quality.
As a reminder: