How does the new importer work?

I agree! One of the many things I’ve fallen behind on :disappointed:

For the import format, Arc can import the JSON files created by its own iCloud Drive backups system. On the old phone, turn on the iCloud Drive backups in Arc’s backup settings, then wait until it completes.

For importing JSON files created by Arc’s manual exporter, here’s some information on how to adapt the format to match the backups format: