Why does the laminate floor sink in in one area?

Either the subfloor wasn't perfectly flat when it was installed, or it was installed with no gaps around the edges to allow for expansion, so it's under stress causing it to raise up slightly, and sink when you put weight on it, i.e. step on it. You could probably run in a squeeeeak no more screw or two in it to hold it down, then fill in the hole with a little bit of wood putty that's the right color, and no one would notice.

Your floor is not level - the underflooring may be damaged....due to many things. Age - wood shrinks with age, Water damage, Warped boards. Many things can cause this. You might have someone look under the flooring to see the problem.

This happening because yours hallway wasn't properly leveled. It is common problem. It can happen in any room, at any type of subfloor, wooden or concrete. You may try to set dividers between rooms. Or you need change direction of planks.