I would not be confortable if my nanny do that. Pls advise your nanny not to that, even in some child care the basic floor rockers are not allowed which im sure theres a good reason for it. Im not sure about damage done. Better to prevent! Take care!
You may do some research here: https://www.google.com.sg/amp/s/sg.theasianparent.com/yao-lan-baby-hammocks-safety/amp https://fb.watch/25M5LKaa27/