It has always been like this. It’s because the breakpoints are based on pixels, and the iPP has a resolution which, in landscape orientation, puts it into the desktop breakpoint. iPad (2018 6th as well) will only load the tablet breakpoint in portrait orientation.
There is likely a custom code way to force the browser to load the tablet breakpoint by sniffing the browser, but you’re likely going to get some weird behavior depending upon how you’ve sized things.
I would also point out that your Nav layout breaks at anything smaller than 1150px. It is always a good idea to check your design by going into preview and making the window bigger/smaller. Your users could be viewing your site on a netbook or just in a browser window on a laptop that isn’t fullscreen, and the nav will be broken for them as well.
The fix is to take your Nav element and make the height auto instead of 100px.