This is correct. To deform/break this spring means it has went into a stack/bind situation.
Obviously this is caused by the added force due to higher operating pressure. Two things absorb this force, the spring and buffer rubber.
If the spring is beefier, it will stack sooner (if using larger diameter wire). The valve needs a certain amount of travel to operate obviously. This also means the buffer would absorb less of the energy.
If I start having issues (I have had one bent spring and now I don’t fill to max), I will probably add some washers, one at a time, made from rubber to the buffer side of the equation. I will add them to the cover side so they stay put. This should put more of the buffering load on the buffer and off the spring.
Dave