I can confirm that the issue has been resolved with the update and my realms have been restored!
This has happened to me today too. And, worryingly, my realms worlds have disappeared in this beta version. I will be very upset if my main world has gone!
This issue seemed to be fixed in the 1.21 update, but returned on my Pixel 9 Pro today.
I can confirm that the issue has been resolved with the update and my realms have been restored!