How to fix this hard normals map?

Basically, I combined 2 meshes together, then applied the normal map from one of the original meshes to the now combined, and that resulted in this hard, cut discrepancy. This problem is hard for me to explain, so I am asking how could this be fixed? Maybe a way to blend normals between the neck and lower head, but how? Idk

It seems there are no UVs for the head of the character… hard to see… are there two different materials ??

No, the mesh is all under one material, and I unwrapped the new head into UVs as shown by the picture

In fact i only now see this little red arrow… so this:

normalHead

is a very consistent normal map… so none… but if this is one material ir would be blueish…

So do you have more than one object here ? Or multiple geomtery… also hardly visible…

Combine the two materials (or perhaps just the normal maps) and paint a mask to blend them at the join.
Like this video…

Jump to 4 min if you dont need to see the PBR setup.

the head did not have a normal map originally, sorry for not emphasizing earlier. so trying to find a way to blend the normals on the neck to hide the cutoff