question about component stress of 2 switch flyback in SpeedFit

WEN

Dear support team,

Could you help me to confirm that component stress in 2 switch flyback in SpeedFit.
I seem the waveform has 1700V blocking voltage when switch off.(demagnetization and Diode clamp to VBUS.)
Why the SpeedFit show blocking voltage is 850V and recommended component utilize 1200V device in initial configure?

I also attached the Speedfit result, please review it.

SpeedFit Silicon Carbide (SiC) Design Simulator _ Wolfspeed.pdf