Sewer line has a pipe into sump pump?
Since we moved in, our landlord had installed a drain from the sump pump all the way out to the curb, which I thought was strange, but whatever. Last night our main sewer line clogged, but I had been noticing it getting worse for the last 2 weeks or so in addition to a sewer smell in my basement. I poured water down the floor drain and the smell did not subside. So today, when the line was snaked, I mentioned to the plumber that any time we flush, shower, use the washing machine, etc. the sump pump kicks on. They insisted I must be mistaken, so I had them try it, and I was right. Someone added an additional P-trap and hose that runs directly into the sump pump from the main sewer line! When I went and looked at the curb, there was visible toilet paper! I called my landlord and he told me that the hose off that sewer line is supposed to connect to connect to my washing machine discharge hose! Can someone please tell me what the heck is going on here? I don't know much about plumbing and know nothing about waste water. Thanks!
Here's a picture to hopefully make it more clear.
Plumbing Issue