Question Unwanted Specular on Terrain

Hello, I'm using a shader graph on a large mesh to use for a terrain, and I've run into a classic Unity problem: the terrain is shiny, no matter the specular and the smoothness value

In a previous project, a programmer had manually coded a shader that could remove these unwanted sky reflections, but can I remove specular reflections from an object/part of an object sing the shader graph?

I tried changing the light, indirect lighting, the reflection probes, removing the light probes, to no avail.

Is there a solution?
Thank you