Footnotes removed when copying a post

### Quick summary

For a post using footnotes, when duplicated/copied, the new post doesn't retain the edits in the Footnotes block.

### Steps to reproduce

1. Create a new post that uses footnotes and add references to the bottom footnotes block
2. Duplicate the post
3. The new post's footnotes block is missing the edits.

### What you expected to happen

The block should be copied as-is

### What actually happened

There are numbered links to the footnotes but no text/edits are retained.


### Impact

Some (< 50%)

### Available workarounds?

No but the platform is still usable

### If the above answer is "Yes...", outline the workaround.

_No response_

### Platform (Simple and/or Atomic)

_No response_

### Logs or notes

_No response_

Reproduce the problem by creating a WordPress post with edited footnotes, duplicating it, and comparing the footnotes block with the original. Trace the post-duplication handling for the Footnotes block, then verify that both the numbered links and their edited text are retained in the copied post.

Written by the indexing model from the issue text.