Image that uses a material is visible outside of Viewport mask of ScrollView

In my project in Unity I have a ScrollView. Scroll panel in Unity has the next structure. Viewport has Mask that makes visible elements of Content only inside this mask.

When in Content I have an Image that uses a material with shader(URP Shader), this image becomes visible outside of Viewport(outside of mask).

Could you prompt me, how can I use my shaders properly in this particular case.