I mean, they couldn’t stand the noise from their neighbours. My only experience of a flat 30 years ago, I hated that aspect, never agan.
But I hope you have spotted a genuine bargain with no strings!
Genuinely, look into service charge/sinking fund matters, is there an horrendous bill on the horizon with insufficient funds, noisy neighbours and little acoustic insulation, complaints about neighbours.
How does it compare to other flats in the block, have they got neighbours from hell (solicitors if you advance this will ask pertinent questions that must be answered truthfully), is there a huge service charge/maintenance/cladding bill in the pipeline? More research is required.