There are different kinds of data:
- Your site’s database
- Your site’s public files (for example, images on your website)
- Your site’s private files (for example, purchase invoice PDFs)
- Server configuration (
frappe-bench/config/*) - Installed apps and their state (which commit is checked out)
- State of your server (installed dependencies, etc)
(1) is typically included in external backups, (2) and (3) are optional. You have to take care of (4), (5) and (6) yourself, if you do self-hosting.
For example, if you have a database backup of a v9 instance, you will have great difficulty restoring it now, because the dependencies changed and it’s close to impossible to set up a new working server with all the old software required (here’s how). However, if you have a full server backup, there shouldn’t be many problems.