Apple Maps will soon rename the Gulf of Mexico to the Gulf of America, following similar changes made by Google this week, in order to comply with U.S.
Edit: it's come to my attention OSM has Gulf of America labeled as a regional title for en-US users. Organic Maps database is an older snapshot and does not reflect the edit yet, but eventually will.
Yeah, definitely better to use open source alternatives. You could potentially change the language to UK English or Australian English and still see the internationally accepted name regardless of which app you use.