That’s strange then as it’s the same underlying architecture on which Nik is running. That’s a very serious bug. I hope DxO fixes it soon. I’m still running Nik 3 which did run reliably on Intel. I don’t have it installed now on my M1 so I don’t know if Nik 3 runs on M1. As you are on Intel, a backgrade to Nik 4 or Nik 3 would make sense.
I have filed a crash report from my Mac Studio max with DxO for crashes from Color Efex - also crashing with Silver Efex, both from Nik 5. No response yet and I am presently avoiding using the programs.