In a community property state, half your income is considered to be earned by your spouse and half your spouse’s income is considered to be earned by you. So 50:50 is the best outcome you can expect.
Your spouse might have an argument to a larger refund for 2018 based on the fact that half her income was earned before the wedding. This should have been part of the original claim, but injured spouse forms are difficult to prepare properly in community property situations and may require expert help.
If your refund letter indicates there is an appeal process, you could try based on the marriage being in the middle of the year.
