I am thinking this has something to do with IRS Form 8615. Since she is considered a full-time student it triggers the questions about her parents income.
Purpose of Form
For children under age 18 and certain older children described below in Who Must File, unearned income over $2,200 is taxed at the parent's rate if the parent's rate is higher than the child's. If the child's unearned income is more than $2,200, use Form 8615 to figure the child's tax.
Who Must File
Form 8615 must be filed for any child who meets all of the following conditions.
The child had more than $2,200 of unearned income.
The child is required to file a tax return.
The child either:
Was under age 18 at the end of 2021,
Was age 18 at the end of 2021 and didn’t have earned income that was more than half of the child's support, or
Was a full-time student at least age 19 and under age 24 at the end of 2021 and didn’t have earned income that was more than half of the child's support.
At least one of the child's parents was alive at the end of 2021.
The child doesn’t file a joint return for 2021.
