The hidden albums can be shown again via the settings in the Xiaomi smartphone's photo or gallery app.

Note: The albums can be selected individually again.

Android 10 (MIUI 12.0)
Step 1:  Open the  Gallery app
Step 2:  Open the  menu
Step 3:  Open the  Settings
Step 4:  Tap on  View hidden albums
Step 5:  Tap on  Unhide
Step 6:  Tap on  OK
  1. Open the Gallery app
  2. Open the menu
  3. Open the Settings
  4. Tap on View hidden albums
  5. Tap on Unhide
  6. Tap on OK

Xiaomi Instructions