If the foot of the bed is broken, put the mattress directly on the ground. Does this affect Feng Shui? If so, what will happen?

I can tell you responsibly that it has no effect on Feng Shui.

Of course, the mattress should be laid directly on the ground to prevent moisture. You can put a piece of floor leather or plastic between the mattress and the ground, and then it is much lower at once, which makes life inconvenient. Change beds as soon as possible.

Good luck.