Sick of Bathroom Mess

I work in a small office (under 10 people). Our new coworker always leaves a mess in the bathroom, They poop almost everyday. How do I know?! SKID MARKS every single time. I think they flush it with the lid down and don't check if it's clean afterward.

Today, I went in right after them and got the cherry on top: a long piece of toilet paper with a skid mark on it floating in the water and hanging over the toilet seat while almost touching the floor.

I'm so sick of this, why do I have to clean up after them every time?! I brought it up to my other coworkers and they said it doesn't bother them that much. What would you do if you were in my shoes? How to bring it up to the new coworker to make them stop?

Any advice is appreciated.