I was too merciful on Twilight the last time, https://www.fimfiction.net/story/411596/marks-for-effort-twilights-reprimanding let's turn it up a bit.

After Twilight bans the CMC from her School of Friendship, after accusing them of a crime they didn't commit, the girls give her a big taste of the cold-shoulder, and this leads to major falling out with not just Twilight, the girls, and friends, but it starts to give her a bad image all over Ponyville, which could soon escalate into worse!