[TENANT-US-MO] Historic plumbing liability?

We live in a top floor of a historic building split into 2 apartments. 123 yrs old . Signed a lease stating that we are responsible for any damaged property, I figured normal use wouldn't cause a problem. Shortly after we moved in (<month), sewer backed up & flooded basement. Floaters etc. LL sends his plumber, he pulls out gobs of "female trash" etc and we're told it's our responsibility to pay for half of what the plumber charged.

To my knowledge we never flushed wipes, tissues, napkins, paper towels, q-tips, tampons, cigarettes, plastic straws or kilos of blow down the toilet, just TP in normal quantity. And we had not been there long enough to do all this.

We are of limited means and sometimes struggle to pay the $1k/month, utilities, gas, groceries. I did not pay what they asked not out of protest, defiance or to call a bluff but simply bc I couldn't afford it. They never pressed me on it, but I was made aware that if it ever happened again it would be on us. Again, I figured it wouldn't, nobody is going to flush anything but TP.,.especially after that.

Our 2 year lease is up in February. Today I found out it's flooded again, same deal. Nobody feels responsible, nobody can afford to pay so nobody wants to tell landlord, we were talking about shop vac the mess ourselves but idk if that's right or if this is really on us. I know shortcuts were taken in renovations. Plumber was just here he had to pull up tiles and saw thru concrete to fix a pipe that had a dishtowel wrapped around it as a previous fix.