It seems that the rewrite of vtkWindowedSincPolyDataFilter (that amazingly improved its performance) also changed how internal surfaces are smoothed. Smoothing of internal surfaces are important because when we segment a medical image we usually annotate many adjacent structures that have common surfaces and when we apply smoothing then we want to smooth surface of each structure and not just the outer surface of the entire segmented region. The old version (VTK8) smoothed the internal surfaces
Subdivision Surface Modifier — Blender Manual
Mesh Smoothing - an overview
Mesh Generation Overview (Tetrahedral)
Soft shape-programmable surfaces by fast electromagnetic actuation of liquid metal networks
Rethinking Contact Simulation for Robot Manipulation, by Toyota Research Institute, Toyota Research Institute
StarCCM] Poly and Trimmed mesh in the same simulation : r/CFD
PDF) Adaptive and robust curve smoothing on surface meshes
Mesh internal surface smoothing behavior changed in vtkWindowedSincPolyDataFilter - Support - VTK
Unity - Manual: Mesh Filter component
Dynamic Mesh - MR CFD - CFD Analysis, Consultation, Training, Simulation
What Is Meshing: Unlocking the Power of 3D Geometry