My contractors plumber has begun to run a long extension pvc pipe across the ceiling of my kitchen. It is not a down pipe and that has me concerned. The pipe is being ran from my toilet upstairs to the stack pipe in the middle of my hallway on the first floor. Originally, the stacked pipe was supposed to be removed and placed elsewhere. Last week the plumber was trying to figure out the best and maybe the easiest place and way. He suggested that he might have to run it across the kitchen ceiling which, runs right above my stove area 👀🤮. I can't imagine if that ever broke or leaked!!! DISGUSTING!! I shutter to think. Upon checking out the work today, I see that he did runnthe pvc pipe in the kitchen ceiling. Unless the toilet has some super force, it seems that not only is this nasty but it might be a clogging issue. That pipe is levelef for a pretty long length before it gets to the stack pipe. Is this normal? Should I be concerned? Please help me if you can. All advice is needed. Not to mention that this pipe is in the hallway closet where my washer and stackable dryer unit will go. It's a tight spot. Thanks in advance. Pictures are below.