My previous workflow is this:
Draw curve -> Extrusion -> Boolean operations -> change of details.

Of course, I can change the workflow to avoid this error:
General shape obtained by rotating the curve -> do Boolean operations.

I know any one of the continuity fillets work well, but continuity fillets is not an exact arc, In many cases, G1 continuity and Circular continuity look very similar, but they generated polygon number is different. Moreover, this is not an advanced CAD software design intent.

This simple model can do, but complex models? Often difficult to change the design workflow。

Thanks BurrMan