Signals Notebook: Will the Entity ID of Admin Defined Custom Object change

No, the ID generated on creation of a custom object is permanent.

Please find detailed explanation below:

On adding a new object of a specific System object type, the Entity ID is generated for that object, such as ado-6:9ee34132-93e2-4ccf-a86c-0606508e7deb. This Entity ID serves as the unique identifier for the object.

It will not change even when new items are added, or properties are updated for this object.