Okay I somewhat understand this, thanks for explaining :)

When they uncouple a locomotive from the train, for example when changing direction at a station, you still need power in the kitchen to keep everything up and running. So when a loc gets uncoupled, this pantograph gets raised. Note that this pantograph was never used when the train was running, only when standing still in stations.

Nowadays in modern restaurant coaches this gap is covered by batteries in the restaurant coach rather than a pantograph.

why the pantograph