Entities card, "attribute" row: "secondary_info" not supported

Configuration Frontend
1

I wonder why the "secondary_info" option is not supported for the "type: attribute" row in the Entities card.

type: entities
entities:
  - entity: sun.sun
    secondary_info: last-changed
  - type: attribute
    entity: sun.sun
    attribute: elevation
  - type: attribute
    entity: sun.sun
    attribute: elevation
    secondary_info: last-updated

image
image1332×599 62.6 KB

OK, the "secondary_info" is not mentioned as supported for attribute rows in the docs.
Was it done by purpose?

Update 04.11.21:
Surely secondary_info is not supported for the type: attribute row since it’s a property of the whole sensor, not an attribute.