The Issue

This is a limitation of how this new feature was implemented, but I'm still adding this to the bug tracker so we are aware that this is meant to be fixed at some point.
When adding blurring steps to the cavity masks in sculpt mode, either with the "Mask From Cavity" menu operator or via the auto-masking options, it will not lead to an ideal result.
The blurring very strictly follows the triangulation of the mesh causing streaks along the surface, and poles grow into star patterns.

This needs a deeper look into alternatives to blur the mask in the operator.