Notion Backups only has access to Notion data (pages, blocks, databases) you have explicitly authorized. Pages, and their children, like blocks, databases, and other pages created after the authorization, won't be backed up. You can always choose which pages Notion Backups has access to in your workspace settings or the Share menu inside your Notion workspace.
In general, it's a good practice to regularly review top-level pages Notion Backups have access to.
Notion workspaces connected before , don't have a comment capability enabled unless you have reauthorized your workspace after that date. To have your comments backed up, reauthorize your workspace.
By default, images, audio, video, and PDF files uploaded directly to Notion will be backed up (for media files hosted externally, only URLs are backed up). This can significantly increase your backup size. You can control this setting from the workspace settings.
Backups are compressed before upload to save on storage space and bandwidth costs.
If you have questions about anything, feel free to reach out.