Some .tor.onion sites are not displaying the underlying V3 onion address in alpha

In Tor Browser 12.5 we display the corresponding V3 onion address in the circuit display when visiting a SecureDrop instance via its human-readable .tor.onion address. However I've noticed it's not working on certain .tor.onion addresses, e.g.:

Working as expected: https://nytimes.securedrop.tor.onion/
Does not work: http://abc.au.securedrop.tor.onion/

Could the double subdomain be the cause?

(Given this is a bug with a recently developed 12.5 feature, I'd like to Backport the fix after 12.5 stable's release if possible please)

Edited Jun 12, 2023 by donuts

To upload designs, you'll need to enable LFS and have an admin enable hashed storage. More information