I was a part resident in one state, worked and paid state taxes, then moved to a different state with the same job. Why do I owe excessive taxes in my old state?

I’ve lived in Oregon my entire life and have always received a refund. I moved to Alabama in October and listed that while filing. It shows I owe Oregon close to $4,000 while Alabama is giving me a $200 refund and I’m getting a $2,000 Federal refund. Why do I owe Oregon so much money?