Apparently this is a known issue, since the help page says
If you have noticed your S2 style has changed to Generator, do not change any of your customization settings, as your journal may revert back to your original layout on its own. However, if you adjust your customizations,
you might not be able to recover your original settings. This issue’s cause is still being investigated, and we apologize for any annoyances resulting from this situation.
But — how long should I wait to see if it does revert? That thing is UGLY. Does anybody know?