Leaving aside the uniqueness of Han Dong.
The two squads here have reached 'Gold' and 'Silver' levels respectively.
The uncertainty and anxiety written all over the faces of Lucius and Diz indicate that they have never encountered such a situation.
If they encounter an 'Overlapping Space', the moment they step into a spatial passage, more or less spatial repulsion would likely be noticed by everyone.
Even if the spatial passage was smooth, Han Dong from the Void Laboratory would definitely sense it.
'Illusion techniques'
The possibility is also not great.
Due to the corruption caused by the 'Whispers' and the 'Indescribable' to the spirit.
All knights who go out of the city for investigation missions are prepared for spiritual protection beforehand, most people would go to the church a day in advance to receive a 'prayer blessing' which lasts for a week.
Therefore, to say that everyone fell into a certain illusion without any signs is not possible.