The encrypted backups do work, but Signal is really, really bad at indicating when and how to make them to use them for restoration. Most non-technical people I know are just resigned to wiping out their Signal history every time they get a new iPhone (and I know two people who abandoned Signal and went back to iMessage because of this), and even I've lost it a couple times.

It leaves sort of a gross taste in my mouth that a paid service is the fix for their unhelpful UX.