Because those members of the National Defense Force were not purely professional soldiers, they showed unprofessionalism in many ways, such as having basically no concept of secrecy.
So, in their chat just now, those militias not only didn't keep secret where the king and his family were staying, but some of them who had participated in previous operations even bragged about various details as conversation topics.
With this information, Leonard Ethan and the other person quickly determined what the target's location was for and confirmed their earlier guess—it was Louis XVI's room.
Since Leonard Ethan and the other person were on the inside of the palace building, there were far fewer patrol personnel here than they had imagined. However, the watchful guard at the entrance made them feel a bit uneasy.
