From the changelog:

9.0.2 - 2023-01-09

Changed

• BUGFIX: When an account has folder_blacklist set but no list of
  configured folders, it now backs up all folders.

9.0.1 - 2022-12-29

Changed

• Made --reset option on migrate optional. Now, existing emails
  in destination folders are kept.

9.0.0 - 2022-12-29

Added

• Options for setting source and destination delimiters for the migrate and mirror commands.

8.0.1 - 2022-09-24

Changed

• Filtered out non-standard flags from migrate and restore.