Maybe my interpretation is wrong and the firework spell was aimed at the devices. I wish it was more clear, as in the WN it clearly states it hit Tomoe as well, and I wouldn't have expected her to have one. Here, we can't really see that but I'm not sure if that's just because of the view or a change. I assumed it had been a callback to the petrification stuff showing that Makoto could make people immune to things but, maybe not.
more novel firework stuff
The part that would make me think it's targeting the devices is that Root says "Did he get them all?" And Tomoe is like "Well, there isn't a second shot, so yea, I guess so". Wish they kept that. I feel like this scene really is the first showing of how powerful Makoto has become, as sure we get some scenes with training some kids and stuff but this is like, wide area, mass target spell that he instantly casts without a single miss