She probably thought that it would be easier to kill her while she was till a bird than when she was a human and could talk
Yea, she was and is a total asshole from the get-go. Think back to her crazy ass villain dialogue before turning FL into a cat. She was salty bc FL was getting a "happy end" despite not "working" for it.
Now it implies lowkey that she thinks of herself as hardworking despite that work being downright selfish and harmful to others (and the work itself not being that hard by virtue of magic acting like a cheat code), + committing matricide. Basically, she doesn't feel bad about any of it.
it means from a young age she was already exposed to sorcery, and while she had the guileless as of a kid to find the situation unfair. she still reveled in having her own mother turned into a bird and possibly having killed her mother by maintaining her form as a bird. the knights did say sorcery eventually wears off... I hope the consequences are just and satisfying.
cheers to the main couple