Burnt taste in hookah :(

A continuation of this post

Noticed my hookah mix(i have yet to find something with nicotine) is burnt near the foil (was actually stuck to the foil so idk if i put too much. and when I say burnt i mean black and stuck to the foil).

If I make one with double the foil will it manage heat better? (also I’m unsure if the bowl should have black spots from charcoal or smth after a session).