Your Oregon 40 is your state tax return so it will show a different tax liability than your federal return. Without examining the returns, I can't say for sure why they are different by the amount of your stimulus payments. But one possibility is that your income is such that you have no income tax or tax withheld, so the only thing refunded is your stimulus payment.
Yes, this is a know complication for Oregon residents...dn not entirely clear to Oregon folks that this is happening....and correctly occurring But it is the way the Oregon tax department is dealing with the stimulus:
as note already by @DawnC
"Yes. The state of Oregon does not tax the stimulus payments or rebate credits directly. Oregon reduces your taxable income by your federal tax liability. But they make adjustments to that reduction. Your stimulus payment(s) and the recovery rebate (if you did not receive your full payments) are subtractions to your federal tax liability number on your Oregon state return. So, the reduction to taxable income is less which equates to a higher taxable Oregon income. "
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....and discussed over and over since at least February: