Streching near edge on unwrapped mesh On the left view (rendered 3D) the material looks stretched and I can't figure out why that is happening, I expect it to work well. It's a fresh project and the plane object has a subdivision modifier applied with adaptive checked.
You have probably unwrapped the UV before you made the margin wider. Mesh changes require UV changes accordingly to avoid distortion. Best to avoid unwrapping unless no further changes to the mesh are planned.

Unwrapped the geometry:


Changed the mesh. The UVs are no more correct:


Corrected UVs: