Was the life of a slave hard in Ancient Egypt?

Yes: Even for a well fed and treated household slave. Remember there were no modern labour saving devices. Every household job had to be done by hand. It was hard graft.

Life was very hard for those slaves forced to do humiliating, degrading and often dangerous work such as working on the land, digging canals, building monuments, and quarrying. They were at the mercy of tough overseers. They were usually naked and regularly beaten.

Life working in the mines must have been unbearably hard.