I'm part of the app's beta testers program (Minecraft Android).

Since the inclusion of beta 1.17.10.20 it is not possible to find diamonds.

It is only possible to find diamond when the world we are playing in were created with the "Cave and Cliffs" option turned on.

I tried to find diamond in both modes of game (survival and creative).

Unfortunately, Cave and Cliffs is causing the Minecraft app to crash and close, so I can't play on worlds created with this option enabled.

In short: the beta version has no diamonds and the beta version with Cave and Cliffs has diamond but it crashes and closes by itself.

Please check.