As mentioned on FB, this is the part that represents the radio direction finding unit. Has a clear cover with some painted or decal detail on the inside. Common on a lot of german aircraft but probably most noticeable on the he219 and ju88g night fighters.
That's the FUG 7 RDF aerial, it was a pretty average system - wasn't quite line of sight but had a pretty poor range and was very unhappy with adverse atmospheric conditions - like bad weather/lightning. The Ju87 wasn't exactly an all weather fighter/bomber.
It was used to find specific RDF frequencies broadcast from the ground but could also tune into other radio signals if they were constand and Strong (radio station) or the nav was very good