Well if you want me to get picky, stall speed goes up with (weight x load factor / MTOW)^aeroelastic coefficient.
For a rigid wing, aeroelastic coefficient is 0.5. For a non-rigid wing, the coefficient varies according to deformation with loading - a hang-glider can well be in the range 0.6-0.8.
That form of the equation is the Venton-Walters equation.
And you're unlikely to find that in many groundschool notes.
G