A landlord in Wisconsin receives two applications for a vacant apartment.
Applicant A has a steady income from a full-time job.
Applicant B has a lower income from part-time work but receives a government housing voucher that covers the majority of the rent, making their total financial resources sufficient.
If the landlord rejects Applicant B solely because their income is from a housing voucher, what is the landlord's action considered under Wisconsin Fair Housing Law?