Her flashback showed that she helped Starlight find a specific magical rock knowing she intended to use it to steal cutie marks, which makes her retroactively complicit in Starlight’s rise to power and the entire Cutie Map and Cutie Remark Crisis.
 
She defended Starlight by saying “she hasn’t enslaved anyone lately” without even being sure she’s actually reformed. She hinted to Starlight that with the right stone, she could rule all of Equestria, and said “Am I?” when Starlight asked her if she was messing with her.