If you filed a joint return, both spouses are jointly and severally liable for any shortfall, error or fraud. That means the IRS can come after both spouses for the shortfall, or only the spouse with more money, or however they want to.
You can file to request "innocent spouse" relief. This would include an argument that you didn't know about the error or fraud because it was hidden from you, or an argument that you should be partially responsible but not wholly responsible ("equitable relief"). The IRS is not bound by or required to follow the divorce order but they can include it as a factor in their evaluation.
(Note that for innocent spouse, you must be divorced at least 6 months and arguing that you should not be responsible for monies due on joint returns. Injured spouse is different, and is for when a spouse wants to be protected from tax debts from before the marriage.)
The innocent spouse relief form can be filed as part of your tax return (if you expect an offset will happen) or it can be filed as a separate claim after you discover that your refund was offset.
See here for more.
https://www.irs.gov/individuals/innocent-spouse-relief
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