One more thing I was thinking.
Let's assume for a moment that the smoke is from the Garden burning.
Who could have set the Garden on fire?
Option 1: FAQ --> All FAQ units should be attending the trial at the moment (only possible way I can think of is the brrom someone mentioned)
Option 2: Haffaton --> Unless they have flyers (I don't remember any mention about them), they should have gone through the walls and Jillian would know.
From Update 66
Jillian liked this space, mainly because she could park a gwiffon on the stone tiles here. Now perched in its saddle, she rested her bare sword across the flat of its neck, and watched the skies. She fully expected Haffaton to attack at any second, with anything they had. But at least if there were an airspace incursion, she could see it from here. If not, she’d at least be aware if the walls were taking damage.
Option 3: Charlie's archons --> Right now it's Haffaton's turn so the options here would be
* Charlie is allied with Haffaton --> Possible, but we've had no indication of it so far. It's hard to think they were allied before the turn started and we've had nothing to assume it might have happened just now.
* Charlie had Archons in Efbaum's airspace before Haffaton's turn started --> Assuming Charlie's turn order came after Haffaton, Olive didn't mention anything about Charlescomm presence in the battlespace. Jillian also has not mentioned any Charlescomm presence in the battlespace once FAQ took control of the city. And it's hard to think the veil the archons might have had could fool Jack.
* Charlie has some other means to set the Garden on fire without the need of presence in the Hex --> Again, we've had no indication so far that this might be possible.
Option 4: Crapsack had somehow returned to Jillian and decided to "go to the toilet" in the middle of the Olive Garden --> That would actually be hilarious
Option 5: Some other means I'm not seeing right now.
Option 6: The smoke is not coming from the Garden