In ‘’Sentibubbler’’, Ladybug (or Pegabug) could have stolen either one of three things from Hawk Moth : the Butterfly Miraculous, the Peacock Miraculous, or the coffee cup that controlled the sentimonster.
She should have stolen the peacock miraculous.
Why? She would have been able to free the feather from the cup and also purify it, as we have seen Mayura doing this to senti!Ladybug, I believe. If Ladybug had stolen the peacock miraculous, she could have made the sentimonster disappear, therefore save Alya’s family, and also she would have had the peacock miraculous, so Hawk Moth would go back to using only the butterfly miraculous again. This would have been a major win for team Ladybug
Instead, she stole the coffee cup, which was a mistake on her part. As Hawk Moth points out, he still controls the sentimonster because he created it and has the peacock miraculous, and therefore decides to drop Alya’s family from the bubbles, potentially killing them in the process. This distraction also allows him to escape because Chat Noir and Ladybug are busy saving the people
It could be that only the person who creates the sentimonster can withdrawl the feather, but I don’t understand why Ladybug chose the coffee cup instead. That cup would have been easy to break during battle, possibly with Cataclysm. Ladybug stealing the cup didn’t do anything
Ironically, Hawk Moth at the end of one episode complains to Natalie that LB never makes mistakes, but she already has made plenty, including this one. She also lost the Bee Miraculous and was partially responsible for some akumatisations










