When I bake the normal map, it gives me the shading artifacts from the low poly mesh.
I tried countless times, but I can't find out what is wrong. Does anyone know what is going on?
Here are some photos, thanks in advance.
The reason that the lighting looks strange is that the low-poly model uses triangles instead of quads. When using smooth shading together with the triangle-based mesh, blender has trouble interpolating the normals.
The fastest solution but maybe not the best would be to simply use flat shading on the low-poly mesh instead of smooth shading.
Ideally, you would want the low-poly mesh to be made of quads. The practice of making a low-poly quad model from a high-poly model is known as retopologizing, and there are tons of tutorials out there on how to do it. This video from CGMatter shows an easy way to do it automatically. Your high-poly mesh seems to already have good topology (i.e. quads), so another option would be to simply make a copy of the high-poly mesh and dissolve some of the edge loops.