Thank you for your support, it works!

I also apply for tailwind like esbuild and it works too!

my config:

config.exs:

config :esbuild,
  version: "0.17.11",
  back: [
    args:
      ~w(js/app.js --bundle --target=es2017 --outdir=../priv/static/assets --external:/fonts/* --external:/images/*),
    cd: Path.expand("../apps/back/assets", __DIR__),
    env: %{"NODE_PATH" => Path.expand("../deps", __DIR__)}
  ],
  front1: [
    args:
      ~w(js/app.js --bundle --target=es2017 --outdir=../priv/static/assets --external:/fonts/* --external:/images/*),
    cd: Path.expand("../apps/front1/assets", __DIR__),
    env: %{"NODE_PATH" => Path.expand("../deps", __DIR__)}
  ]

config :tailwind,
  version: "3.2.7",
  back: [
    args: ~w(
      --config=tailwind.config.js
      --input=css/app.css
      --output=../priv/static/assets/app.css
    ),
    cd: Path.expand("../apps/back/assets", __DIR__)
  ],
  front1: [
    args: ~w(
      --config=tailwind.config.js
      --input=css/app.css
      --output=../priv/static/assets/app.css
    ),
    cd: Path.expand("../apps/front1/assets", __DIR__)
  ]

...

config :back, Back.Endpoint,
  ...
  watchers: [
    esbuild: {Esbuild, :install_and_run, [:back, ~w(--sourcemap=inline --watch)]},
    tailwind: {Tailwind, :install_and_run, [:back, ~w(--watch)]}
  ]

...
config :front1, Front1.Endpoint,
  ...
  watchers: [
    esbuild: {Esbuild, :install_and_run, [:front1, ~w(--sourcemap=inline --watch)]},
    tailwind: {Tailwind, :install_and_run, [:front1, ~w(--watch)]}
  ]

apps\back\mix.exs:

  ...
  defp aliases do
    [
      setup: ["deps.get", "assets.setup", "assets.build"],
      test: ["ecto.create --quiet", "ecto.migrate --quiet", "test"],
      "assets.setup": ["tailwind.install --if-missing", "esbuild.install --if-missing"],
      "assets.build": ["tailwind back", "esbuild back"],
      "assets.deploy": ["tailwind back --minify", "esbuild back --minify", "phx.digest"]
    ]
  end

apps\front1\mix.exs:

  ...
  defp aliases do
    [
      setup: ["deps.get", "assets.setup", "assets.build"],
      test: ["ecto.create --quiet", "ecto.migrate --quiet", "test"],
      "assets.setup": ["tailwind.install --if-missing", "esbuild.install --if-missing"],
      "assets.build": ["tailwind front1", "esbuild front1"],
      "assets.deploy": ["tailwind front1 --minify", "esbuild front1 --minify", "phx.digest"]
    ]
  end