The lack of preparedness of Al Nassr's defenders was evident from the moment Al Ahli attempted their first attack, and it was clearly a poor start.
I also agree with your opinion that Al Nassr is overly focused on attack without considering their significant defensive weaknesses.
Jorge Jesus should have a solution to this problem, as if left unchecked, it will undoubtedly worsen Al Nassr's title challenge once the season starts.
Nor just Al Nassr, most big teams out there put their focus mostly on the attacks first only to later find out they needed their defence as much as they need the attack. The attack of Al Nassr is very brilliant and they often use it well enough but I believe they have seen clearly now for sure that they are going amd supposed to work on the defence so that they can have that balanced squad they. Will be even more result orientated.