> A profile folder has everything. You can copy it, back it up, plug it into a completely new Firefox installation later.

These new profiles seem to be slightly different from the old ones?

[edit: ignore most of the stuff below, see replies]

The new UI doesn't show your other regular profiles and when you create a new profile via the new UI, it also doesn't create a separate profile folder (it's part of your active profile). They're like sub profiles... probably to allow everything to be synced via a Firefox account?

We can still move the profile folder. The difference is that what's created with the new UI is part of that folder (the old about:profiles page is still there and old style profiles are still supported).