Have you got the inpit_deps set in .formatter.exs? The ecto setting should stop that. However, as someone pointed out, it will randomly screw it up every now and then. You have git to save you in those instances.
[
import_deps: [:ecto, :phoenix, :surface, :nimble_parsec],
inputs: ["*.{ex,exs}", "priv/*/seeds.exs", "{config,lib,test}/**/*.{ex,exs,sface}"],
subdirectories: ["priv/*/migrations"],
...
