An authority-ordered housing ban immediately changes how a rented apartment can be used. The lease consequences depend on the exact order, its start and duration, and the use that remains possible. Rent, maintenance, access and a possible termination must each be assessed against those facts.
The order does not replace the tenancy-law assessment. It identifies the use prohibited for public-law reasons. Section 1096 ABGB and, where the Austrian Tenancy Act applies in full or in part, sections 3 and 8 MRG determine which consequences the restriction may have between tenant and landlord.