The Squish command itself has not changed its algorithms in the WIP. TestSquishPhysicalStrain and TestSquishGeometricalStretch are currently the only way to access the new algorithms in the WIP.
At this point I’m fairly certain these new algorithms will not make it into Squish in the commercial release of Rhino 9. The test commands will probably stay.
A couple of bug fixes and small enhancements were made to Squish in the WIP. I have a few more on my ToDo list, including better texture mapping and getting the “ARAP” algorithm introduced in the Squish command. Hopefully I can get to them before the release of Rhino 9.
The ShapeMap Grasshopper plugin is now being distributed with all installations of Rhino WIP and brings a complete redesign of the Squish workflow to Grasshopper, as well as the more robust “ARAP” algorithm. Have you tried it?
As Tom said, I can’t help much here without a 3dm file, the command parameters, and the results you wanted to see.