The listing says this home has a long list of recent home improvements;
they apparently fixed the ceiling but forgot to cover up the improvements. More than likely they were covering up cracks but with an older home it is hard to match paint. As a stager I would most definitely point this out to them as something that needs to be addressed. One quick coat (hopefully) over the entire ceiling should do the trick.
Even if you had to hire a professional, fixing the ceiling the right way would be much less costly than a price reduction or lower offer on your property. Always remember the details when preparing your home for sale or find someone who will pay attention to those details for you, like a professional Home Stager. Or, as my husband said, “I guess there is the hope that they never look up!”