One possible reason could be that she is hiding her identity. Maybe she has a secret mission or she's trying to avoid being recognized by certain characters in the fanfiction world.
She might be wearing a mask to protect herself from something. For example, there could be a disease spreading in the fanfiction setting, or there are harmful substances in the air. Another reason could be that she's been injured on her face and doesn't want others to see. Wearing a mask can also add an air of mystery to her character, making her more intriguing to other characters in the story.
In the fanfiction, Sakura could be wearing a mask as part of a cultural or religious practice. It might be a symbol of her status, like a sign of being in a particular group or having a certain role. Also, it could be a disguise for a prank or a game she's playing with other characters.
Chapter 141, "The Recruitment Contest!", is the clearest early answer because it turns Chixia Village's situation into a concrete plot event. A useful checkpoint is the way the scene starts with It had happened in the afternoon when Aunt Ying's son and daughter...
Chapter 342, "Founding Ceremony, Childhood Sweethearts, Did the Star-picking Hall Catch Fire?", is the clearest early answer because it turns Meng Qiuning's situation into a concrete plot event. A useful checkpoint is the way the scene starts with Inside the shrine, there were a total of seven spiritual tablets, two... and follows through with Did the Holy Tripod explode?" "The Holy Tripod is further back, look,....
Chapter 45, "Give a Sweet Date and Then a Slap", is the clearest early answer because it turns Wen Jiaojiao's situation into a concrete plot event. The chapter turns that into something concrete by moving from Helplessly, Jiang Yan had no choice but to step on the accelerator.
Chapter 37, "Those in the know anticipate the transformation, while the oblivious think it's a fashion show.", is the clearest early answer because it turns Hello's situation into a concrete plot event. It opens with The barrage was suddenly filled with hahas, but the two guests...
Chapter 1, "I'm Not Interested in Uncultured Men", is the clearest early answer because it turns Sister Li's situation into a concrete plot event. The chapter gives readers a real answer by opening on Jiang Li, I'm warning you, don't set your sights on Yinwan anymore,...
Chapter 150, "Has She Been Cursed?!", is the clearest early answer because it turns Zhang Cheng's situation into a concrete plot event. The chapter turns that into something concrete by moving from Upon hearing the first part of Jiang Li's words, Zhang Cheng...
Chapter 233, "Individual, Ten, Hundred, Thousand... Million, Ten Million, Damn!!!", is the clearest early answer because it turns Director Sun's situation into a concrete plot event.
Chapter 70, "Irresistible Stunning Charm", is the clearest early answer because it turns Jiang Li's situation into a concrete plot event. Early on, So, under the curious gazes of everyone, Jiang Yan strutted up with.... By the end, He Yun was also surprised as he looked towards Jiang Li..
Chapter 163, "She Actually Gave President Shang a Zero?!", is the clearest early answer because it turns Wanwan's situation into a concrete plot event.
Chapter 348, "Scheming and Being Schemed Against, East Ridge Five, Zhu Yang's Threat, The Dust Settles (Part 2)", is the clearest early answer because it turns Zhu Da's situation into a concrete plot event. It opens with Lu Yang of East Ridge, ready for your instruction!" As number three's... and closes on Zhu Yang also stood up, glaring at Zhao Hu with a particularly unkind....