Hi iacdxb,
If I’m not wrong, these files I got were from a tutorial series here, I’m not certain if you have changed something. If so, please point out what, thanks. The file is a bout a curtain and not an object covered with a cloth, except the stage floor counts as object.
There are certainly several influences, but Stiffness and Flexion are certainly the parameters to have an eye on. Of course the density of the mesh as well its quality is a key, please have a look here
https://www.cineversity.com/vidplaytut/better_cloth_deformations
The tools mentioned in “Function” are now in “Mesh”.
The Bounce is crucial as well, as it (at least in my understanding) simulates as well as the air cushion between object and cloth. This leads with the structure of the object to a different result. Use a Landscape object (set to spherical) instead of a sphere.
I hope that helps, perhaps you have a different scene, then I certainly have a look into it.
All the best