Yes it works fine when I view your site.
I also managed to test it using an emulator to simulate a really old version of safari, and this too was okay.
Sorry, I don’t know what would cause the issue that you have described.
Are you manually adding the Google maps iframe to the page? If so, have you tried a dedicated maps plugin to insert the map. It might be worth trying as a plugin would be designed to handle this.
Is it the same issue as described here: https://stackoverflow.com/questions/34320046/iframe-height-issues-on-ios-mobile-safari ?