Description

When debugging the the issue #69315 found that when installing a block from inserter and then saving the post the block plugin doesn't install and block disappears.

This issue does not occur in 6.7
This issue occurs when Show Template is enabled

Step-by-step reproduction instructions

1. Click on inserter and search for a new block
2. Install the block and save the page
3. The block disappears and the plugin is not installed

Screenshots, screen recording, code snippet

• Trunk Show Template enabled

• Works fine in 6.7 Works fine without Show Template enabled

Environment info

No response

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