the top surface is supposed to be smooth yet it isn’t? Anyone knows why?
You might have some duplicated vertices. Go to edit mode, in vertex mode select all the vertices, then press alt+m and choose by distance.
This came up in another thread a day or two ago, or perhaps I saw it somewhere else. I think the solution was to go into Edit mode and Alt+H to unhide hidden vertices. I may be wrong.
Ah yes some vertexes were hidden thanks!