They don't know the mass of the planet yet, so surface gravity is an unknown as of yet. The paper suggests two scenarios: a rocky world (~7 earth masses) or a

They don't know the mass of the planet yet, so surface gravity is an unknown as of yet. The paper suggests two scenarios: a rocky world (~7 earth masses) or a water world (~2 earth masses). Surface gravity would be 38m/s² for a rocky planet (~390% earth's surface gravity) and 8.2m/s² for a water world (~84% earth's surface gravity). I'm not an astronomer so I don't know if anything in between those values is a realistic scenario, but I wonder how you got your 125% of earth's surface gravity.