I have an "other deductible expense" but I did not enter any? Thoughts?

There are two alternatives to determine which deduction method to use.  You can either get the Standard Deduction or the Itemized Deduction. 

The Itemized deductions are the list of home mortgage interest, real estate taxes, state taxes, medical expenses. Many of these deductions have limitations.

The standard deduction for 2021 is: 

For single taxpayers and married individuals filing separately, the standard deduction is $12,550.

The standard deduction for married couples filing jointly for the tax year 2021 is $25,100.

For heads of households, the standard deduction is $18,800.

If your deductions will exceed the standard deduction you should give it a try.