setup
indesign 16.1
macOS 11,2,1
2 more monitors plugged on the computer

steps

• plug the iPad om the macbook pro 2016 on macOS 11,2,1

• open sidecar in the system preferences and connect the iPad

• open indesign. it opens on the macbook pro screen

• try to move the inDesign app windows on another monitor

expected results
- the indesign app windows is moving in the big monitor

actual results
- it doesn't move
- just the document windows is moving on the other monitor

note : if i disconnect the iPad in sidecar of the system preferences, it works