This is pretty common to see for tiles, if you are on not beta Godot, autotiling is essentially broken anyway. Beta godot has made some wonderful changes to tilesets though.
Viewing post in Sprout Lands - Asset Pack comments
Yeah, I'm on Godot 3.whatever-number. Not the new Godot 4 hotness. I don't really mind how it handles Autotiles but some tile sheets (like the dirt and hill sets from this pack) don't have a tile for every possible position. So it makes the Autotiling a little wonky. I can use it up to a point. Then I have to go pack to the tile atlas to fine tune stuff.
Not the end of the world but figured I'd make sure I wasn't missing something.