Wrinkels at bottom of cloth

Good evening (o;

Tried now the cloth physics in 2.8 for the first time after watching a youtube tutorial…

Added two torus as collision and a plane with 100 subdivisions as cloth…
after cloth simulation I added subdivision modifier set to three for viewport…and I see at the bottom jagged cloth like from the first subdivide…but at the op the cloth is smooth as it should be…

Anything I missed here?

I’ve set quality steps to 15 and collision quality to 5.

thanks in advance
richard