If I gave my employer 4 weeks notice before I quit to move across country, can they require me to sign a form stating I can be fired at any time between then and now and will be unable to get unemployment benefits? Is it legal for them to make me sign thi

I finally got the date of my families move set and planned and let my employer know, I gave them 4 weeks notice. Today in my tip envelope they had given me a form to fill out stating my final day and that I could be fired at any point in time from now till my final day and that if I was fired for any reason I understood I would be unable to receive unemployment benefits. My boss left a hand written note to sign it and place it on her desk. Is this even legal? I also noticed all my appointments for the next month has mysteriously been canceled or moved to someone else.