I was just about to report it as well, and they disabled that ability apparently...
Google has removed the button to report a location as incorrectly labeled from the Gulf of America.
Some users claim they’ve left reviews objecting to the renaming, but a quick scan of the Gulf of Mexico — now labeled Gulf of America depending on your location — reveals that the most recent review is from a month ago.
I was just about to report it as well, and they disabled that ability apparently...
(source)