--format ignore_file not working as intended?

Environment

• Elixir & Erlang/OTP versions (elixir --version):

Erlang/OTP 24 [erts-12.2] [source] [64-bit] [smp:10:10] [ds:10:10:10] [async-threads:1]
Elixir 1.13.3 (compiled with Erlang/OTP 24)

• Which version of Dialyxir are you using? (cat mix.lock | grep dialyxir):

  "dialyxir": {:hex, :dialyxir, "1.1.0", "c5aab0d6e71e5522e77beff7ba9e08f8e02bad90dfbeffae60eaf0cb47e29488",
[:mix], [{:erlex, ">= 0.2.6", [hex: :erlex, repo: "hexpm", optional: false]}], "hexpm", "07ea8e49c45f15264ebe6d5b93799d4dd56a44036cf42d0ad9c960bc266c0b9a"},

Current behavior

I'm not sure if I didn't correctly understand how it's supposed to work, it seems to me that when I pass in the option --format ignore_file, the output is the same as when I don't pass in any --format option, and thus cannot be used for .dialyzer_ignore.exs?

I'm looking at the output to stderr.

Expected behavior

The output by mix dialyzer --format ignore_file can be used in the ignore file.