In the document "Begründung" it says on page 7: "The Erschließungssystem enables a temporary preservation of the buildings Wieslocher Straße 2 ("Plattform") during the settlement." This means that the buildings at Wieslocher Straße 2 can remain standing while the redevelopment of the area has already begun. The grey hatching represents the existing buildings, which are planned to be demolished according to the plan. However, this remark does not concern you if you are interested in a single-family house plot here: it is marked on the property of a multi-family house block.
P.S.: the "Plattform" is a counseling center for homeless people.