I have set up Entity Usage to track a 3-tier relationship:
Custom Entity type >> [entity reference] >> Custom Block type (block_content) >> [layout builder] >> Node
I have this patch applied https://www.drupal.org/node/3119521 → though it may not be relevant.
When viewing the usage of my custom entity, I correctly see it as "Live on page" when I"ve placed the block type that references this custom entity on a node using layout builder. When I remove the reference to that custom entity from the block, and save a new revision, I correctly see the entity's usage list say "Translations or previous revisions". However, if I instead remove the block entirely from layout builder and save a new revision, it continues to say "Live on page", even though the block is no longer there.
The problem is that when removing the block entirely from Layout builder, the block itself is not changed from being its default revision, even though the relevant node revision is no longer its default node revision.
Needs review
2.0
Code
This patch checks if this is a custom block, and if so, if it has a parent that is no longer the default revision, it will change the wording to "Translations or previous revisions" instead of "Live on page".