What’s an “Attribute special row type”?
That’s where I found the suffix:, but what is or how is the “Attribute special row type” different from any other use of the entities card?
The entities card can show entity states on each row but it also has the ability to show other things, like attributes, buttons, dividers, sections, etc…
The suffix option is listed under the attribute special row, not the entity state row. Hence you can’t use it for bog standard entity states, only when showing attribute states.
Look closely at the documentation I linked to, suffix is under the attribute type. That is the only place you can use it. The options for entity rows are listed above that. Those are the only ones you can use for an entity.