Roofs with lots of different patches—some newer cement, some old sealant, some random tiles stuck in—often tell a story of repeated leakage fixes. Each patch may have solved a leakage for a while, but if there are many such areas, it might mean the underlying waterproofing was never fully redone.
A few small repairs are normal. But if large sections are covered in mismatched materials, you can guess that top-floor flats have probably battled seepage more than once.
It doesn’t mean you must run away, but it does mean you should ask direct questions and understand when a proper full-surface solution is planned.
