First a disclaimer: I created a mod that changes the color of the operative’s icon depending on its visibility state (Hidden, Located, Revealed). It’s thanks to this mod that I found lots of strange things related to infiltration.
In a nest, I destroyed a poisonworm egg … but when I then moved close to it’s former location my operative’s icon changed to “revealed” (surprise). So I did a few tests and found out that if I destroyed the little “nest” that was under the egg my operatives remained “hidden”.
That’s because the “nest” on which the “egg” rests is a “ItemContainer”, is not counted as dead and has a “perceptionBase” stat of 5. So it reveals my operatives if I don’t shoot it.
If it was a targetable enemy I could understand, but there you have to manually aim to get rid of it. So it points me to an unwanted behavior, therefore a bug.