Why is the sunrise equation graph on my Apple Watch inaccurate?

If you have an AppleWatch, you have a complication to see the sunrise equation (see picture). That line, which will be a sinus indeed, should flatten out or become sharper depending on the latitude where you are on the planet (something your AppleWatch knows) and depending on the day of the year. The closer you're to one of the poles, the flatter the line should be, right? The line should give me a clue about how fast the sun will rise. In my case; in the Netherlands, the line should be rather flat, the sun rises and sets slowly, and in the United Arab Emirates, the line and curves should be sharper; the sun rises fast, and sets fast too.

Well, it isn't.

If it would be the same line, wherever you go, I could live with that (although it pains me that nobody at Apple seems to have that Obsessive Attention to Detail any longer), but that's not what happens either. The sharpness of the curve does change depending on the day of the year, at least, so it seems.

All clarification on this matter is greatly appreciated and if that means lecturing me on how this graph is meant to be and where I went wrong in my reasoning, that is greatly appreciated too.

[Re-Titled by Moderator]