Sometimes spring manufacturer gets to fix a spring problem and not create from the beginning. I once read about a company that had an oil tempered spring which was zinc plated. The story behind this was that the springs often broke because of the hydrogen embrittlement.
Everything resulted in a change of spring material and the problem was solved. This is something that meets the torsion spring industry all the time, even though it wasn’t about torsion springs in this specific case.