I've heard that the app was useful to refresh people's memory when doing contact tracing, but as the cases went down quickly after the app was released then it might not have been a gamechanger.

the app is open source of people are interested; https://github.com/aranja/rakning-c19-app

Couldn't you DDoS this infrastructure by having beacons masquerade as users and then have people quarantined because they were marked as near an infected individual when in reality they were near a rogue beacon that spams generated identifiers? This certainly can't be constitutional in any Western system of government.

Even if the identifiers were encrypted with a public key that only the tracer service had the private key to, couldn't a bad actor register as a bunch of actual people and then have them show as coming in contact with infected people?

No. All this app does is record a user’s location for the last two weeks. Then, after a positive diagnosis, that location data is examined as an aid to help determine who that person may have come into contact with.

Beacons, identifiers, constitutions, and public keys don’t come into it.

Those beacons would be quickly identified for being motionless, or if they are carried by a person then it's basically someone lying on the app about being infected. This could be verified by medical testing before publishing the ids.

Stick it on a bus or a drone, now it's not motionless.

Or DDoS society.