Navigation button

If I understand the question correctly you must have moved the map. You can zoom or rotate the map while on a trip and then the navigate button appears to get you back to forward-facing-up. If you don't touch it for a few seconds it will automatically do it.

I think Uber recommends it because they like to play with the route to maximize their share. It might not be the most efficient for you but it works in their favor.

I'll take Google over Uber maps.

Also Uber maps never used night mode unless I forced it in the settings. Super annoying. Google goes to night mode automatically. Android.

You'll get it eventually. I didn't even know it had a night mode until I searched for it here. The default is auto and it doesn't work.