Why isn't Heat (Fire) energy considered Non-Basic Fire Energy?

[Puite]

Other special energies that provide Fire energy, (such as Burning Energy), I understand are not being eligible for Fire Energy manipulation targets, such as Candela or the ability Roast Reveal (Salazzle).

But Heat (Fire) Energy specifically includes the Fire symbol in its name.

Why wouldn't Heat (Fire) Energy be considered (Fire) Energy for cards that don't specify "Basic (Fire) Energy"?

 

[PokePop]

Heat Energy says in it's text that it only provides Fire Energy while in play.
Yes, it is confusing that the symbol is on the card. That's why they changed the templating for effects like this to start saying "Basic {X} energy" starting with the Scarlet & Violet sets.