There is bleeding from the wrist to the hands, the blood from the internal bleeding is dying and accumulating under the skin of the palm. The red and purple spots of the palms will feel tender. This is bad carpal tunnel surgery.
If you turn your palms towards your face and look at the wrist of a healthy hand, you will see some small veins near the surface. Underneath them among the muscles that go through the wrist to the hand are blood vessels that supply blood to the muscles of the fingers. The surgical incisions have cut open the blood vessels running through the muscles and the cut vessels are not healing but leaking.
If you keep your hand raised in the air, gravity may help keep the blood from flowing into the palm. With less blood flow, the internal pressure on the blood vessel walls will be less. Leaking should be less. That would give the blood vessels more time to close and heal.