I was sure the age gap between them was around 4 to 5 years, (Since Tsuyu and Chie should be in either 1st or 2nd year of middle school an Yuu was in college presumably in its 1st or second year as well) from this chapter we can assume that its now between 2 to 3 years. (Since Yuu its now clearly at the very least in its 2nd highschool year). The change it self must be releated how they are trying to present the relationship between the Tsuyu and Yuu.
Also Chie remembering to make one for poor Sensei was great too, Chie is awesome and deserves more screen time (outside just teasing and helping Tsuyu)