This may not help, but there was a time when I thought that the dampened spring wasn’t sufficiently configurable and behaved in very strange and erratic ways.
In the end the problem was not that the spring wasn’t configurable but that it attached to the center of my 2D scene by default. When I reparented it to associate it with the player, the problem went away.
Thanks for your answer,
I finally used PinJoint2D with a little bit of softness. It works way better and luckily not distinguishable from a spring in my case