Deactivating the hiding of objects that are out of camera view

GameObjects that are out of the camera view hide by default. I have an object with a shader and the shader makes the object look bigger then it actually is. That leads to hiding the object, while its actually still visible.

Is there a way to disable that hiding of objects or increase the distance or something?

Yes there is. Unity uses the AABB of the mesh to determine if it’s in the viewing frustum or not. You would need to set your own Bounds for your mesh. To just double the original AABB size you can just do

Bounds bounds = yourMesh.bounds;
bounds.extents *= 2f;
yourMesh.bounds = bounds;

Though if you know the possible range that your shader might manipulate the vertices you could be more thoughtful about how you setup your bounds.