Ok, A63 is one of the large fields featuring also a
large town (217 buildings). Only over those I get puffy. But still, no gun in the objects list for those bases that possibly could shoot auto puffy
UPDATE: I hovered over such a base in the puffy and disabled the standard auto acks (GNG) one by one. Some of them apparently had the ability to generate puffy as well, because when I took them out, puffy dwindled down and then stopped.
At this point, it almost sounds like a bug to me.