The plumber came.
He fixed it.
What was wrong? Something we could not have seen if we tried. A pipe behind a wall was broken and water was seeping up through the grout on the floor! It was not the bidet. That just happened to be the low point on the bathroom floor so all the water puddled there. We could have tried all kinds of things and never solved the problem. Because we didn't understand the cause. The plumber knew because he’d seen it before and he understands how these apts are built. A small part and a few minutes work was all it took. It took 3 days to dry the bathroom out after that! But no more puddling. No more stink.
I paid someone to come clean up after the problem was fixed.
All of life should be so easy.