Shell doesn't cover the entire inner wall at some areas
You should increase the top layer thickness according to Ultimaker Cura support:

Top/bottom thickness
With the top/bottom thickness you can set the thickness of the solidly printed top and bottom layers of the print. A higher value ensures all gaps on the top and bottom layers are closed completely. However, this can also increase the print time and amount of filament used.
It is advised to always use a multiple of the layer height for the thickness of the top and bottom. This means, for example, that with a layer height of 0.15 mm, it’s better to set the top/bottom thickness to 0.6 mm rather than 0.7 mm.