Australia's contact-tracing app sends quite a bit of personal data to a centralized Amazon server. It lets users enter a pseudonym but demands their real phone numbers, so in effect the centralized server will know the identity of each user.

The description of the anonymous IDs that phones will exchange is not clear to me. I can't tell whether this really protects users' privacy or not. I would appreciate a pointer to a report by someone who has studied the real details.