I found 3 bugs:
- It appears that I can't remove landfill that I placed before installing the Landfill plus mod, unless I ran over it (normally it doesn't let me delete landfill right under me, I guess this resets the condition somehow).
- removing landfill by robots doesn't give me the item back (even though "Recover landfill" option is checked), removing by right-click does recover the item
- removing landfill doesn't preserve the shallow water (unless i remove the landfill with concrete on it)

(FYI I'm using Krastorio 2 and Space exploration mods)

I have another issue to add, same mods, having landfill unlocked from the begining of the game removes the recipe and doesn't let me build it at all. That also disables recipes like Waterfill from CanalBuilder.

I tried removing all related mods, but only unchecking "unlock at start" and forcing the load managed to fix it.