That’s literally the law Ontario courts rulled cannot apply to topless women as it is discrimination.

On July 19, 1991, a sweltering and humid day, Gwen Jacob, a University of Guelph student, was arrested after walking down a street in Guelph, Ontario while topless after removing her shirt when the temperature was 33 °C (91 °F) and was charged with indecency under Section 173(1)(a) of the Criminal Code