Uneven floor and Vinly Install

[Robert Hernandez]

Hello BP family

Recently bought a quadplex. And one of the unit I went into has an issue on the second floor where one of the room hardwood floor is wavy. I can feel like a speed bump in one spot in the room, is that like a foundation beam? Visually it is kinda hard to see.

But the vinly wood in the room does not look good, alot of it is raised and weird. I am think the person who installed it did not leave enough expansion gap. Because the room looks fine but there are alot of gaps and buckling in the wood. Other room with the same vinly looks great.

I plan to install vinly again. But would the speed bump be an issue? Or can I level the wood somehow? Also, since it is on the second floor is a self leveler concrete very bad or can damage the property since its heavy? Or should I just install carpet?

The bottom floor doesn't appear to have foundation damage. The house is built on a slab and the bottom floor is even. Just the upstairs kinda concerns me. Thank you!