Uber tells you how to shoot, not what size
If you came looking for an Uber Eats pixel size, Uber’s restaurant menu photo page doesn’t give one. It gives a method: indirect window light, the right angle for each dish, the filling visible, the portion readable, and the photo taken as soon as the food is plated. Fixed ratios and minimum sizes quoted elsewhere for Uber Eats restaurant photos aren’t on the Uber pages we read.
In practice, size is rarely the problem with a photo from a current phone. Light and accuracy are. Uber’s review looks at whether the photo truly represents the dish, so a well-lit phone photo of the real plate is a better bet than a polished image of a version you don’t serve.