I agree 
About our game Puffy Cat: in Box2D 3.0 something has been improved in the implementation of joints, as @notbadgun has removed our ‘hacks’ for legacy Box2D and as the result the soft body works as before. Great! 
One thing that got worse: it’s the interaction between kinematic and dynamic bodies. We have platforms implemented through kinematic, which we move through position changes. And this leads to undefined behaviour of dynamic bodies. On legacy Box2D everything works ok, it manages to handle this, but on Box2D 3.0 unfortunately dynamic bodies go crazy. In short, this is the feature request that needs to be made that we can fully transition to the new Box2D: Physics 2D: moving a kinematic object with linear_velocity and angular_velocity · Issue #10446 · defold/defold · GitHub