Hi Anis, thanks for the video attachment!

But that's actually not the area of the model that has the split-up edges though, they are in this area:



Also one note on the technique you are using there in the video - although that works, you may want to try and avoid that method when possible since it creates a surface that has a collapsed down "pole" point in it - you can turn on the surface control points to see that.

Surfaces that collapse down to a pole can sometimes cause problems, they tend to need special processing for things like determining the surface normal at the pole point.

It can also work fine, it is just something that can be a good idea to avoid if possible since they are more complex. Generally a model that contains a smaller amount of "pole" areas like that is better quality.

In the kind of case that you are showing, there is a different way to construct it without any pole, which is to make a solid and do a boolean to cut it with an angled profile line, like this:





If you turn on control points for this method, you can see that the surface is instead a very simple plane, with trim curves on it, rather than one that collapses down to a pole point:



Basically the booleans will make an extrusion of the profile cutting curve and that extruded surface is intersected with the main shape to form that cap with this method - such extruded surfaces are more simple.

- Michael