This may be a clue -
If the instruction say to bake Hi-Tek Heat Set Supercoat at the higher temperature, its TGIC free?
https://www.pfonline.com/articles/are-tgic-free-powder-coatings-right-for-you
What part of it's not a powder coat don't you understand?
So you're saying the roast I did the other day might have TGIC because I set the oven at 350.
Powder coat is a dry powdery substance that's a PAINT. Hi-Tek is a liquid.