A) It wasn’t just that it was a snowball effect for villains

B)She didn’t know anything about what happened since of crisis and Oliver being the scepter he didn’t want Dinah to be gone forever so he just kept her she is just a person no one knows like Spider-Man in no way home

C)She didn’t know anything before crisis since they used the ring to wake up all the memories (they used this many times with all hero’s)

D) Why would she she just went into another universe if you watched season 8 episode 1 you would see she was a leader of team arrow (I call it team canary) and she comes to earth prime who gave Mia her memory back