Your chair is shrinking
Not dramatically. It knows better than to make the change obvious.
It lowers itself by tiny, deniable amounts while you sleep.
You sit down in the morning and suddenly the desk feels taller. The keyboard appears to be on a different floor. Your knees have moved into an arrangement no adult body approved.
People will talk about posture, cushion compression, and hydraulic cylinders.
Very technical. Very convenient.
But chairs are observant. They know when you are tired, and they use the opportunity to renegotiate the seating arrangement.