Why does backfill disappear?

[Vases1987]

The black soil is constantly growing and any filling on this soil disappears. How to fix it ?(1).png[/attachment]

[Koub]

What mods do you use ?
This maybe : https://mods.factorio.com/mod/TerrainEvolution ?

[GrumpyJoe]

Since there are pY buildings in the picture, I'm guessing it's the tar pit or whatever it's called.
AFAIK that only happens if it's over filled?

Try pY forums and how to deal with that

[Vases1987]

No, I don't have such a mod. There are alien biomes, but when I turn it off, the area still increases, and the embankment disappears and very slowly goes along it.

[Vases1987]

Yes, the "Pyanodons" mod. Thanks. I'll try to search.