Block translation in the cloned page will also update same block in the source page

Problem/Motivation

Drupal core 8.9.11

Related to https://www.drupal.org/project/drupal/issues/3062819 🐛 Cloned entities don't retain their Inline Block usage Needs work

Updating translated custom block on the cloned page will update the same block on the translated source page. The same will happen when updating translated custom block on the source page - it will update the same block on the cloned page.

Exactly the same was happening to layout builder custom blocks and it's described here - https://www.drupal.org/project/drupal/issues/3062819 🐛 Cloned entities don't retain their Inline Block usage Needs work . Patch: https://www.drupal.org/files/issues/2021-07-15/drupal-3062819-16.patch → has fixed this issue for the origanl language content but not to the translated content that uses Layout Builder Symmetric Translations module.

Steps to reproduce

1. Clone a page that is built with Layout Builder (I use Entity Clone)
2. Edit Layout of the cloned page in other language - translate one of the blocks and save the Layout
3. Go back to the original content (from which the page was cloned) and edit layout in the same language as in point 2.
At first you will see that everything is correct but when you try to 'Translate block' in the popup block window the text of the block is the same as in the cloned page. It means that editing translated block on the cloned page will apply the same changes to the same block on the source page (from which the page was cloned)

Proposed resolution

Perhaps a similar patch that fixed this issue to Layout Builder would work? Issie described here: https://www.drupal.org/project/drupal/issues/3062819 🐛 Cloned entities don't retain their Inline Block usage Needs work

Remaining tasks

User interface changes

API changes

Data model changes