Minecraft version
1.14.4 1.16.2

Mod version and malilib version
1.14.4:litematica-fabric-1.14.4-0.0.0-dev.20191222.014040
malilib-fabric-1.14.4-0.10.0-dev.20+arne.2
1.16.2:litematica-fabric-1.16.2-0.0.0-dev.20200824.031346
malilib-fabric-1.16.2-0.10.0-dev.21+arne.1

Description of the bug
I read the code and saw that you replace the grass path but i still see the grass path in the material list.

That PR/fix is only in the master branch ie. the 1.12.2 LiteLoader version currently, and even there it's not in any builds yet. It will come to the other versions with the next update from 1.12.2 at some point.