Description

The Amazon Kindle Embed block in the Gutenberg editor should display a default state (Amazon Kindle Embed - "Embed Amazon Kindle content.") when no URL is entered [Working correctly].

However, upon embedding a URL, the block incorrectly reverts to displaying the default text instead of the Kindle one.

Step-by-step reproduction instructions

• Open a post/page in the WordPress Gutenberg editor.
• Add a new block by clicking the "+" button.
• Search for and insert the "Amazon Kindle Embed" block.
• Observe the default text in the block:
  - Expected behavior: The block displays: Amazon Kindle Embed - "Embed Amazon Kindle content."
• Enter a valid Amazon Kindle URL in the block's URL field and press Enter.
• Expected behavior: The block displays: Amazon Kindle Embed - "Embed Amazon Kindle content." [SAME like other blocks]
• Actual behavior: The block displays the default placeholder text (Add a block that displays content pulled from other sites, like Twitter or YouTube.) instead of rendering the embedded preview.

Screenshots, screen recording, code snippet

• When no URL is added:
  
• When URL is added:
  

Environment info

• WordPress version: 6.8
• Gutenberg version: 20.0.0
• Active theme: Twenty Twenty Five

Please confirm that you have searched existing issues in the repo.

• Yes

Please confirm that you have tested with all plugins deactivated except Gutenberg.

• Yes

Please confirm which theme type you used for testing.

• Block
• Classic
• Hybrid (e.g. classic with theme.json)
• Not sure