Water piping always more copper &stainless steel to plastic.
Insulation nowadays only slightly better. Mostly triple-glazed
windows with right thermal & sound insulation.
Often damaged roof connections & degrees at flat roofs.
Central heating older as of 1985 needs to be changed for emission reasons
A lot of concrete was used. (concrete conducts cold e.g mold can be the consequence) Mostly great and effective floor plans. Flat roofs with moisture problems. Often water pipe problems, outdated Heating systems.
Partly aluminum windows, uninsulated frames, still often single glazing Concrete damage balconies & loggias due to inadequate sealing.
Plaster damage inside and on the facade. thin interior walls. Leaking gas pipes. Lack of fire protection such as fire service directions and fire protection doors