The floor drain in the kitchen is flooding up with sewage and dirty things

According to the analysis of the situation you described, it should be that the main drainage pipe is blocked, and the pool drains from the floor drain if it can't go down, and there may be 2 blockages: 1The connection between the horizontal pipe and the vertical pipe. 2.Standpipe (Main).

The pool is on a high place.

So the water is normal.

But the pipes below are blocked.

So it will gush out of the floor drain.

If the sewer pipe is blocked, or the drain drain is too slow, first look at the size of the drain hole and what structure it is, and then test the sewer.