Defense really fell apart and got lazy those last 7-8 minutes. They had a big lead, a 22-23 point lead, and knew they could get whatever they wanted offensively, so stopped giving that intensity on the defensive side.
This could easily have been a 25+ point lead instead of 15 if they just kept up that defensive intensity and focus. Just too much cheating into the paint and passing lanes and so real late on closeouts meaning a lot of barely or not contested threes that went down for the Pels.