How to smooth shading glitches around edge The red mark is the mesh beside the groove. How do I make it smooth?
The green mark is what I want to make smooth.

I have used some cutters that are hidden. If you wish you can unhide and see it. I have added subsurf of level 4. Yet the mesh is not smooth some parts.
To be scared even more you can use Zebra matcap shading in viewport.
Issue raise more visible.

You can change Data Properties &gt; Normals &gt; Auto Smooth &gt; Angle to 14 in this case, that make the Normal Shading better, but it doesnt fix it entirely.

Both issue makes even beter with SurbSurf 5.

... but since cuts are far from folowing base topo, it generates a lot of Ngons with unpredictable triangulation. I think Retopo is waiting for you :)