well fire sparks have shown up on midoriya more, i don't recall it on all might that much. Except for his eyes, where it looks like void/with two burning embers pupils that glow intensely. (he was also able to draw the remaning power in one for all before it expired)
and also his punch, can change the weather to rain, this would only be possible if his punch are causing heat!
It starts to rain after he let loose his power/intense punch.
Well imo, I think there is heat aspect to midoriya and all might (All might eyes intense glow and his punches can warm up the temperature) Also All might could not unlock past holder quirks, so it would make sense one for all is giving echo of that ability. but more weaker form from soul copy.(weird as it sounds)
I will wait for more story. Because it subtle clue.
Just like all might explanation to sucking up air, to become mucles (sound like balloon explanation, but that requires heat/fire to become big)