We purchased two Crazyflie 2.1 in Feb 2021, and four more in Jan 2022.
For all of the quads, we use the firmware from https://github.com/bitcraze/crazyflie-firmware with the commit head de913f40a09792b7b41f3f37b3e75a2311c28b51.
I use the now deprecated ROS wrapper from https://github.com/whoenig/crazyflie_ros
With the same firmware and ROS wrapper, the two Crazyflies I got in 2021 is able to hover properly under Vicon using the the launch script hover_vicon.launch. However, the four new quads do not behave correctly using this set of code. Specifically, the new quads seem to jump up and down erratically. We have doubled checked the relevant ROS topics and they all seem to be correct. We also ran a hardware version check and there seems be no problems either. We also tried to fly the new quads using teleop with an xbox joystick and they worked ok, at least the operator did not feel anything wrong with the new quads.
We would like to know if there are some differences in these two versions of Crazyflie 2.1 which may have caused the issue. Please let us know if you need any other info. Appreciate your help!

Tom