Recently I was in database view and a global change went wrong (please tell me we have all been there). We do regular backups of our database but I found out that if you revert to a former version of RE 7, even by 15 minutes, NXT goes to a factory reset, wiping out a lot of essential data we spent hours putting into NXT. There should be a way to revert to a backup, which is kind of the point, without losing all NXT data. Otherwise we would be forced to manually change the bad data, or pay extra money for a temporary database to export and reimport all the NXT info.
We just went through this (June 2020). If you need to revert to a prior backup of your database, you WILL LOSE anything in NXT that is not stored in database view (e.g., lists, workflows, opportunity status history, action attachments, etc.) Basically NXT goes back to ground zero if you need to restore. A huge vulnerability, spread the word!!!
See also this Idea: https://renxt.ideas.aha.io/ideas/RENXT-I-292.