Maternity Leave Retaliation?

Hi, I have a co-worker that went out on maternity leave in September of last year, being paid through Washington State's paid medical/family leave program. She was gone about 4 months, and any time I spoke to her, or anyone spoke about her, it was always "When [name] gets back." Well she's back, and management has changed all of her responsibilities to that of a lower position, i.e. work location is now customer facing, supervisory duties are gone, and a support function that interfaced with a different team is gone. All done under the guise of "We didn't know if you would be back," and "This is where we need you now." It seems like a slap in the face to her. My question is, what is more important legally: the position and it's duties, or the pay rate? They haven't cut her hours or her pay, they've just moved her. Company has under 20 employees.