I’ve found some context here : NavMesh: Paths don't follow NavMesh surface - #10 by Cedric
and related PR : expose seed and computepath smooth by CedricGuillemet · Pull Request #265 · BabylonJS/Extensions · GitHub
IIRC, default path computation is straight and does not respect navmesh geometry. The change improves path computation with more respectful to corridors and heights.
I’m all in with recast.js replacement as long as features available and documented are present 