diff --git a/src/flask/app.py b/src/flask/app.py
index 65e95623..360916db 100644
--- a/src/flask/app.py
+++ b/src/flask/app.py
@@ -10,6 +10,7 @@ from itertools import chain
 from threading import Lock
 from types import TracebackType
 
+import click
 from werkzeug.datastructures import Headers
 from werkzeug.datastructures import ImmutableDict
 from werkzeug.exceptions import Aborter
@@ -23,6 +24,7 @@ from werkzeug.routing import MapAdapter
 from werkzeug.routing import RequestRedirect
 from werkzeug.routing import RoutingException
 from werkzeug.routing import Rule
+from werkzeug.serving import is_running_from_reloader
 from werkzeug.urls import url_quote
 from werkzeug.utils import redirect as _wz_redirect
 from werkzeug.wrappers import Response as BaseResponse
@@ -908,12 +910,18 @@ class Flask(Scaffold):
             The default port is now picked from the ``SERVER_NAME``
             variable.
         """
-        # Change this into a no-op if the server is invoked from the
-        # command line. Have a look at cli.py for more information.
+        # Ignore this call so that it doesn't start another server if
+        # the 'flask run' command is used.
         if os.environ.get("FLASK_RUN_FROM_CLI") == "true":
-            from .debughelpers import explain_ignored_app_run
+            if not is_running_from_reloader():
+                click.secho(
+                    " * Ignoring a call to 'app.run()', the server is"
+                    " already being run with the 'flask run' command.\n"
+                    "   Only call 'app.run()' in an 'if __name__ =="
+                    ' "__main__"\' guard.',
+                    fg="red",
+                )
 
-            explain_ignored_app_run()
             return
 
         if get_load_dotenv(load_dotenv):
diff --git a/src/flask/cli.py b/src/flask/cli.py
index 77c1e25a..6e0359d9 100644
--- a/src/flask/cli.py
+++ b/src/flask/cli.py
@@ -11,6 +11,7 @@ from threading import Lock
 from threading import Thread
 
 import click
+from werkzeug.serving import is_running_from_reloader
 from werkzeug.utils import import_string
 
 from .globals import current_app
@@ -273,7 +274,7 @@ class DispatchingApp:
         self._bg_loading_exc = None
 
         if use_eager_loading is None:
-            use_eager_loading = os.environ.get("WERKZEUG_RUN_MAIN") != "true"
+            use_eager_loading = not is_running_from_reloader()
 
         if use_eager_loading:
             self._load_unlocked()
@@ -546,12 +547,6 @@ class FlaskGroup(AppGroup):
         return sorted(rv)
 
     def main(self, *args, **kwargs):
-        # Set a global flag that indicates that we were invoked from the
-        # command line interface. This is detected by Flask.run to make the
-        # call into a no-op. This is necessary to avoid ugly errors when the
-        # script that is loaded here also attempts to start a server.
-        os.environ["FLASK_RUN_FROM_CLI"] = "true"
-
         if get_load_dotenv(self.load_dotenv):
             load_dotenv()
 
@@ -637,7 +632,7 @@ def show_server_banner(env, debug, app_import_path, eager_loading):
     """Show extra startup messages the first time the server is run,
     ignoring the reloader.
     """
-    if os.environ.get("WERKZEUG_RUN_MAIN") == "true":
+    if is_running_from_reloader():
         return
 
     if app_import_path is not None:
@@ -653,10 +648,10 @@ def show_server_banner(env, debug, app_import_path, eager_loading):
     if env == "production":
         click.secho(
             "   WARNING: This is a development server. Do not use it in"
-            " a production deployment.",
+            " a production deployment.\n   Use a production WSGI server"
+            " instead.",
             fg="red",
         )
-        click.secho("   Use a production WSGI server instead.", dim=True)
 
     if debug is not None:
         click.echo(f" * Debug mode: {'on' if debug else 'off'}")
diff --git a/src/flask/debughelpers.py b/src/flask/debughelpers.py
index 27d378c2..b1e3ce1b 100644
--- a/src/flask/debughelpers.py
+++ b/src/flask/debughelpers.py
@@ -1,6 +1,4 @@
-import os
 import typing as t
-from warnings import warn
 
 from .app import Flask
 from .blueprints import Blueprint
@@ -159,16 +157,3 @@ def explain_template_loading_attempts(app: Flask, template, attempts) -> None:
         info.append("  See https://flask.palletsprojects.com/blueprints/#templates")
 
     app.logger.info("\n".join(info))
-
-
-def explain_ignored_app_run() -> None:
-    if os.environ.get("WERKZEUG_RUN_MAIN") != "true":
-        warn(
-            Warning(
-                "Silently ignoring app.run() because the application is"
-                " run from the flask command line executable. Consider"
-                ' putting app.run() behind an if __name__ == "__main__"'
-                " guard to silence this warning."
-            ),
-            stacklevel=3,
-        )