You lost

Bei Sangyun neither agreed nor disagreed with Head Master Fei's proposal. However, they began the game with the bet in mind.

They agreed to play three matches, with the overall victor being the one who won the most matches.

Bei Sangyun was familiar with the rules of Go, though she hadn't played in a long time. 

Back then, Old Master Lin had just passed away, and as the heir, she needed to secure the support of the other family heads associated with the Lin family to solidify her position. To enter their circle, she learned to play Go, using the matches as a way to bond with them.

She picked up skills from various places, such as the streets and some unknown Go clubs, and encountered different styles and strategies.

Unfortunately, she was unable to practice effectively because, in order to curry favor, she always had to make mistakes and deliberately lose. Thus, she was unaware of the full extent of her skills.