If you were unmarried as of 12/31/21, you should have filed as either single or perhaps head of household for 2021. You would not be allowed to file as married filing jointly, even though you were married for part of the year, and there is no way your refund for 2021 would have been issued as a joint check with your spouse.
Is is possible this was a check for the 2020 or earlier tax year that was cashed late? Maybe there was an amended return for a previous year, or maybe a check was lost and re-printed. The tax year that corresponds to the refund should be printed on the check.
You can check your tax return for 2021 by getting your IRS transcript.
https://www.irs.gov/individuals/get-transcript
If you filed a joint return with your spouse for 2021, or your spouse filed for you, you can re-file as a single person or as head of household. However, if you don't have copies of what you originally filed, it will take some detective work to figure out how to file (you might file an original single return or an amended return). I think you will probably need the help of a professional tax preparer. There will also be issues if you try to change from married to single since you can't file a return as married filing jointly unless both spouses agree, so making the correction may involve explaining to the IRS how it happened that you allowed someone to file an incorrect return in your name.
You also won't be able to just get a new check, the old check has to be accounted for. For example, if you can prepare a return under HOH that shows a $3000 refund, but your spouse already cashed a joint check for a refund, your share of the joint check will come out of your expected refund. (The IRS will see the joint check cashed and will assume that you benefitted from the check. It's not their responsibility to make sure spouses split things fairly. That's something that should have been addressed in your divorce. Or if you allowed your ex to take advantage of you, that might be a new civil matter between you. The IRS won't re-issue a check if someone already cashed it.)
I think you may want professional assistance here.
