It´s in the Chapter where to search for the 14 Chickens.
The House with the sleeping chestnut has a Lamp where i have to siphon of the light with the empty lamp from the cupboard.
I think i tried it right, because when searching for a solution i even found a walktrough video which shows how to do it.
Shortly: It does not work on my Mac Os 10.6.8 Humble Bundle bought 21.04. to suck the light out of lamp. Basically nothing happens.
greetings
Ps: I love this game btw :-)