>change status to married with no dependents from single at job.

This.

If there is only one job total among the both of you, this is the correct choice.

We both work full time and bring in two spectate Incomes

Then you should have gone through the W-4 carefully.

>Step 2: Multiple Jobs or Spouse Works

Depending on how different the two jobs pay, it can be as simple as checking that box, using the worksheet, or going through IRS withholding calculator.

Without any other changes, this tells them to withhold taxes like your spouse does not work. This means they assume you get both your and your spouse’s standard deductions and lower-income-tax-buckets.

this is why. Change your W-4 back to single or if you keep it as married then you both need to check the "spouse works" box in step 2c of the W4

You need to revisit your W4 and adjust for both of you working. It is Step 2 on the form ‘Multiple Jobs or Spouse works.’ You can also request higher w/h amount. I believe there is an online calculator you can use to figure out the amounts but do it now so that you don’t get surprised come tax time next year.

Refund went down: https://reddit.com/r/personalfinance/comments/111j2s2/why_did_my_tax_return_go_down_omnibus_edition/

> But other than that no major life changes.

So other than those major life changes, you didn't have any major life changes?

Your federal witholding changed because your filing status and income changed. Simple as that