This is most likely due to the Light or Dark mode you have chosen on your mobile device. If you have selected Dark mode, your device tries to force apps to use a dark background and white text.
Since the HH Membership Card has a graphic background that is light in color, your membership details become obscured because your device is forcing our App to use light-colored text.
We are working on a permanent solution for this issue, but in the interim, you can simply set your phone or device display to "light mode" which defaults text to a dark color.
iPhone/iOS: Go to Settings > Display & Brightness > then choose Light Mode.
Android: Go to Settings > Display > then choose Light Mode.
Relaunch the App and your membership details should be visible again on your Membership Card.