upload another picture...

It's all about sanding I believe.

Is the flooring all the same? Where they treated the same way?

I like to sand between coats myself. The finish tends to raise the grain.

When I did my floors I did between 3-5 coats.

I think it's about the floor and like John said sanding between with the last coat having the finest sandpaper... it made it better when I did that. Also it's important each coat cure properly. More coats may have been needed because it's soaking into the wood? you need at least two but three maybe. John's the pro so go at least three?

Hardly a Pro when it comes to finishing. Still a rookie there. I have been learning the hard way on my own home. Trial and error.

I think the time of year affects things as well. Now the wood is a little more thirty I think.