Kitchen sink cleanout?

clean out? This a plugged vent? Or a clean out missing a cap? I’m thrown off because the horizontal access is screw capped, and the vertical is smooth with no cap. The kitchen sink is opposite this wall, no leak under it and not backing up.

Thanks again!

P.s. its rice all over the ground.

Don’t try and trouble shoot what is going on with the drain. Just report the open drain line and recommend a plumber correct it. There is a lot that could go wrong if not correctly fixed.

Thanks Mike!