Rising damp?

A few months after I moved in, I noticed these weird marks around the bottom of the bedroom wall, which looked as though the paint had been washed off.

And that the paint was flaking off one of the walls.

On closer inspection, you could clearly see that this had happened several times and had just been painted over.

I now know the former issue is called tide marks.

And that both issues are a sign of risking ramp.