Alright so for starters, this weird monster didn’t appear this early in the novel. (I haven’t gotten far so I don’t know exactly when or if this monster even made an appearance.)
And secondly, the MC didn’t reveal her powers this early in the story. The school would’ve taken notice of her ability (and intelligence when she showed a superior formula in class) BEFORE she uses her powers publicly for the first time, when saving the prince (fiancé) who was in Berserk mode iirc.
The novel even had smug prince and twin sister be proud of their high magic power in front of the whole class when in fact it’s a HUGE demerit.
Also, the way she first met Nao-lookalike and the female friend in this chapter were also different, but it’s nothing significant.