Ok so for some context:

I am employed by a company who has clients. There have been ongoing issues with one client since before I even started and last week they dropped us. Long story short I’ve been used as the scapegoat.

The client dropped us on a Monday night. My boss only informed me 2 days later.

Since then there’s been a reshuffle. They’ve offered me a part time position with an hourly rate or to keep the salary but with more work. I already have one foot out the door so I chose the part time to buy me time to find an alternative.

Anyway we formally in writing between yesterday and today agreed to a schedule and hourly rate. I asked to confirm that this would take effect from Monday but they said no it takes effect from “last week” because that client is no longer with us.

My point is: is it legal for them to retroactively reduce your pay without written or oral agreement? I’m aware I work in at-will state but the caveat from what I see online is that they can’t do this for “wages already earned”. I worked my full time hours last week and this week so far so technically isn’t this now wage theft?