Now I found another thread with a similar case:
It seems like the problems there were the support and the orientation of the object. Plus maybe that the printer wasn’t level. Maybe I have the same cause. Also I the table I’ve been using is not very stable.
But there was something in a reply there that I didn’t understand:
"First off, you have the bottom of the cube parallel to the build platform which will cause issues because the first layer will be much larger than the supports holding it up and the layer will fall apart as it peels before doing the next layer. "
Could someone expand a little bit on this. I think that there’s something that I need to get a grasp on here. Why will “the layer will fall apart as it peels before doing the next layer”.