Weird "undermesh" or doublemesh in sculpt mode when using grab tool (begginer)

Hello! Well, im trying my hand at scultping in blender for the first time so i watched some tutorials and got to it. But when i started trying to deform the initial sphere with the Grab tool, i noticed that it didnt move all together, if that makes sense. I tried to push the sphere in, and some parts of the mesh stay in the same place. I dont know what it means, but the best way i have to describe it is it looks like theres a second mesh underneath because the cut from one to the other is so sudden. Here is a picture.

No matter how much I pull at the spherical part, it doesnt move, and it looks like im pulling a second mesh underneath or something.

Then the spehere is finally pulled, but it moves independently of the other part, even though they are the same mesh.

Im in sculpt mode, began with an ico sphere, turned on mirror to sculpt. As far as i know theres only one mesh, no duplicates. I thought maybe its the inner faces but i turned on backface culling so i have no idea. Is this a bug or is it just some limitation of Blender? Confused since the tutorial i saw had no such problem.

Thank you

In Sculpt Mode only the actual object is sculptable… if you have an additional object in the scene (at the same location)… then you see something like this…
There are different settings like for example radius and falloff which do influence the sculpting…

(Also the grab toll does have a yellow “ring” for me… like some of the icon colors (blue, red yellow) suggest…)