It’s more that the human body can be really fucking weird. Your vitals can drop to extremely low levels, your temperature can drop to room temperature, you can appear entirely dead for over an hour, but still recover.
Usually this happens to old people who were already at death’s door. It can be very hard to find any sign of life sometimes.
Not really necessary anymore. If they weren’t dead before, once someone has gone through the modern embalming process they will very definitely be dead afterward.
It sounds like they were paying attention and responsive:
At 2:09 p.m. funeral home workers unzipped the bag, and, according to DeNoto, discovered that Balducci “was still breathing and had a pulse.” The funeral home called paramedics, who intubated Balducci while rushing her to nearby John T. Mather Memorial Hospital. When Balducci got there, DeNoto said she was “noted to be unresponsive.”
“She was placed on palliative care and held on until 5:20 a.m. on February 5, 2023,” DeNoto said. “At that time, she passed.”