State tax filing

Yes, the state of Missouri sent a letter about a week after it sent the adjusted check. I am looking at the letter, but there is no explanation for *why* it was adjusted, just a statement that it *has* been adjusted. As a consequence, I do not know how to appeal. Or what exactly I am appealing. I don't know what documentation they require. It's a little dystopian that the state can substitute its preferred reality (apparently, one in which I owe tax), with no explanation.

The letter just says I can file a written appeal within 60 days and can provide any documents I would like considered. Has anyone else encountered this? How did they appeal (i.e., what did they provide - just a statement that they worked remote 100% for 2021, or something more)?