Ah got what you mean now. I get the option to copy those backup files to Drafts 4, but not Drafts 5. I’ve tried uninstalls and updates to see if Drafts 4 was overriding Drafts 5 in any way, but no such luck. Perhaps this is a missing option? One for @agiletortoise to confirm I think.
Hi! This seems to be an issue with iOS. You can use this Apple Shortcut and share the file to it (by tapping “Shortcuts” in the bottom row of the share sheet and then “Force open in”) and the resulting share sheet should have an option to “Copy to Drafts”.