Mushroom killer Erin Patterson's appeal explained

Mushroom murderer Erin Patterson's appeal against her triple murder conviction will be heard on Wednesday August 19 and Thursday August 20. Patterson is serving life in prison after she killed family members using poisonous death cap mushrooms hidden in a beef wellington lunch. She was sentenced to a non-parole period of 33 years in September last year. Why does she insist there's been a miscarriage of justice?