Yep, pretty much. 1 1/2" pvc with 2 90's going into the stack. The lateral line has may be a 1/4" in 20' . Enough for grey water but not grease and sludge. The dishwasher drains into that line. She scrapes the dishes before washing but......
I bet it has been years since it's been cleaned out. What ever it is, it's pretty solid at about 6'. I vote for a new line amd a couple 45's for the win.