The previous version of the Uber Driver App showed you your rating, but not how it was calculated.
So you had no idea of how many different star ratings you had and so no idea of how vulnerable you were.
The new Uber Driver App gives you this detail.
Tap your profile image in the upper right corner of the main screen. You'll see three buttons, labelled Earnings, Profile and Account.
The Profile button will have your picture above, along with your current rating. Tap it and it will show you your image and rating again, plus your total number of trips and how long you've been an Uber driver.
You can also click the Add Details button to add more personal details that your riders can access if they wish to do so.
Click the rating itself underneath your image to see the breakdown of individual ratings. Your current Uber Driver rating is calculated from your last 500 rated trips.
You can see from the image that my rating of 4.99 is actually made up of 493 5-star trips and 7 4-star trips.
This means that my actual rating is (493 x 5) + (7 x 4) / 500.
This gives 4.986, which is then rounded to 4.99.
So what happens if I get a rider who gives me 4 stars?
(492 x 5) + (8 x 4) / 500 = 4.984, which would be rounded to 4.98.
But if my next rider gives me 5 stars, it has no effect at all. Either the oldest of the 500 was a 5-star ride, so it drops off, to replaced by the latest one, having no effect on the calculation, or (if I'm really lucky) the oldest was one of the 4-star rides, so the new calculation becomes (494 x 5) + (6 x 4) / 500 = 4.988.
Which would still be rounded to 4.99.
So all in all, my rating of 4.99 is actually quite vulnerable.
But at least with the latest version of the Uber Driver App, I can monitor how it's made up and do my best to keep it high.