Hey Nimue,
thanks for bringing this back to our attention! This will be related to the PBR (physicallly based rendering). The lighting adjusts slowly when atmosphere switches are too extreme (which happens quite quickely) just like how an eye adapts to a sudden strong light, after being in the dark.
We can take a look into making that lighting switch to the photobooth more consistent.
(Giving the camera a short time to adjust before taking the snapshot)
Sincerely,
Kevin