Cards are sorted based on the
point multiplier * point value for each card, then in the order in which you have sorted the cards in the My Cards view.
You can see the computed value in the
Value: line at the bottom of each card when you expand a pointer based on the equation above.
If a card’s points are worth only 1c to you instead of the app’s default value, you can change the Point Value for that card, then everything will be re-ordered as you're expecting.
This comes up most frequently for users with Chase Freedom cards, and since most users pair a Freedom card with a Sapphire or Ink, they can then transfer their points to travel partners which more than doubles their value for most people, which is why the default value for Chase Ultimate Rewards points if 2c.
You can customize the point value of any of your cards by tapping on the card, then Customize Card, and use the +/- stepper to increase or decrease the point value based on your valuation.
Note that you can tap on the label to enter a value via keyboard.