The device DV/DT rating is the safe maximum rate of voltage change across the main terminals when the device is NOT being deliberately triggered.
It's a value which may cause unwanted triggering if exceeded.
Think of the device having internal parasitic capacitance from MT2 to gate as a simple example:
If the rate of change of voltage across the power terminals is too high, that capacitance may supply a high enough internal gate current pulse to make the device falsely trigger.
That is a DV/DT problem.
As I've already said, in a basic single phase control circuit with no other parts causing fast, high-energy pulses across the device, it's irrelevant.
Just use a snubber, which is good practice anyway.
All the information you keep asking about is supplied by the device makers in the data sheets. It's there for a reason - so you do not have to derive the parameters and safe working limits for yourself!