I have a low poly model with smooth shading enabled on all faces. unfortunately, when I go into rendered view, I see odd sharp lines on the edges and tris not previously seen in lookdev view: Rendered view: Edit mode:
Try recalculating normals ctrl+N in edit mode or merge vertices by distance also in edit mode I think alt+M for the merge
Its probably due to lighting does it still persist when you move your light source around, and from the image of your node editor your normal map isn't applied yet.
Your low poly and high poly maybe rendering on top of each other. Check your render and view toggles in the Outliner.