In my bathroom, I realized the contractor had painted over a patch of
wallpaper, and I ripped it up as it was loosening from the wall. The
painted wall in this section has always looked like the wall wasn't
smooth or they painted over a clump of something.

I continued to rip, thinking that I was ripping up more wallpaper,
however I realized I was ripping up what appears to be brown paper
that seemed to have the consistency of a paper grocery bag. Is that
brown paper what is called drywall face paper? I do see drywall under
the brown paper layer. If it isn't face paper, should I continue
ripping the stuff off and then prime and paint the wall? If it's
relevant, the bathroom is in a condo that was built in the mid-1970s
and was renovated a couple of years ago.