Linear velocity is a Vector by which RigidBody moves. It describes the change of positions, a vector of difference between position now and position later. Thus it cannot be tweened with a global position vectors, this would give ridicolous results.
You need to rethink what is it You really want to interpolate. Direction of moving object ? Speed ?
The way your code looks it seems like You want to directly tween global_position of the body. This is not advised, collisions won’t be properly reported that way. Instead interpolate speed. Take direction to your target before tweening ( object position minus target position ), tween custom variable speed from 0 to desired number and in process() apply_impulse() using your normalized direction * this speed.
Sorry, it works with
tween.interpolate_property(self,“linear_velocity”,null,Vector2(100,0),1,Tween.TRANS_LINEAR,Tween.EASE_IN_OUT)