Ezra and Samaritans

Prefacing by saying I am obviously not Jewish, my knowledge of Judiasm is through a Christian lens as I was raised that way, although I am not a Christian personally anymore.

Now onto my question, why did Ezra reject the Samaritans help when Cypress the Great allowed the ancient Judahites to return to Jerusalem to rebuild the temple? As far as I can see, the reason given was that they had mixed blood with the Assyrians who conquered the Northern Kingdom, but did not the people of the Southern Kingdom do the exact same thing with the Babylonians and get punished by God for it? I feel like the Samaritans should have still been considered Israelites, but that’s why I’m here to see what y’all were taught.