diff --git a/doc/faqs/how-to-use-composer-behind-a-proxy.md b/doc/faqs/how-to-use-composer-behind-a-proxy.md
index 58f82ebcb..ebefaced0 100644
--- a/doc/faqs/how-to-use-composer-behind-a-proxy.md
+++ b/doc/faqs/how-to-use-composer-behind-a-proxy.md
@@ -104,15 +104,3 @@ Setting the value to `*` will bypass the proxy for all requests.
 
 Composer originally provided `HTTP_PROXY_REQUEST_FULLURI` and `HTTPS_PROXY_REQUEST_FULLURI` to help
 mitigate issues with misbehaving proxies. These are no longer required or used.
-
-## Requirement changes
-
-Composer <2.8 used `http_proxy` for both HTTP and HTTPS requests if `https_proxy` was not set,
-but as of Composer 2.8.0 it requires [scheme-specific](#usage) environment variables.
-
-The reason for this change is to align Composer with current practice across other popular tools. To help
-with the transition, as of Composer 2.7.3 the original behaviour remains but a warning message is 
-shown instructing the user to add an `https_proxy` environment variable.
-
-To prevent the original behaviour during the transition period, set an empty environment variable
-(`https_proxy=`).
diff --git a/src/Composer/Console/Application.php b/src/Composer/Console/Application.php
index 3a784f8a8..7c511f994 100644
--- a/src/Composer/Console/Application.php
+++ b/src/Composer/Console/Application.php
@@ -43,7 +43,6 @@ use Composer\EventDispatcher\ScriptExecutionException;
 use Composer\Exception\NoSslException;
 use Composer\XdebugHandler\XdebugHandler;
 use Symfony\Component\Process\Exception\ProcessTimedOutException;
-use Composer\Util\Http\ProxyManager;
 
 /**
  * The console application that handles the commands
@@ -383,8 +382,6 @@ class Application extends BaseApplication
         }
 
         try {
-            $proxyManager = ProxyManager::getInstance();
-
             if ($input->hasParameterOption('--profile')) {
                 $startTime = microtime(true);
                 $this->io->enableDebugging($startTime);
@@ -406,14 +403,6 @@ class Application extends BaseApplication
                 $io->writeError('<info>Memory usage: '.round(memory_get_usage() / 1024 / 1024, 2).'MiB (peak: '.round(memory_get_peak_usage() / 1024 / 1024, 2).'MiB), time: '.round(microtime(true) - $startTime, 2).'s</info>');
             }
 
-            if ($proxyManager->needsTransitionWarning()) {
-                $io->writeError('');
-                $io->writeError('<warning>Composer now requires separate proxy environment variables for HTTP and HTTPS requests.</warning>');
-                $io->writeError('<warning>Please set `https_proxy` in addition to your existing proxy environment variables.</warning>');
-                $io->writeError('<warning>This fallback (and warning) will be removed in Composer 2.8.0.</warning>');
-                $io->writeError('<warning>https://getcomposer.org/doc/faqs/how-to-use-composer-behind-a-proxy.md</warning>');
-            }
-
             return $result;
         } catch (ScriptExecutionException $e) {
             if ($this->getDisablePluginsByDefault() && $this->isRunningAsRoot() && !$this->io->isInteractive()) {
diff --git a/src/Composer/Util/Http/ProxyManager.php b/src/Composer/Util/Http/ProxyManager.php
index 0571780fe..247105fa5 100644
--- a/src/Composer/Util/Http/ProxyManager.php
+++ b/src/Composer/Util/Http/ProxyManager.php
@@ -33,20 +33,8 @@ class ProxyManager
     /** @var ?self */
     private static $instance = null;
 
-    /** The following 3 properties can be removed after the transition period */
-
-    /** @var bool */
-    private $ignoreHttpsProxy = false;
-    /** @var bool */
-    private $isTransitional = false;
-    /** @var bool */
-    private $needsTransitionWarning = false;
-
     private function __construct()
     {
-        // this can be removed after the transition period
-        $this->isTransitional = true;
-
         try {
             $this->getProxyData();
         } catch (\RuntimeException $e) {
@@ -96,16 +84,6 @@ class ProxyManager
         return $proxy->toRequestProxy($scheme);
     }
 
-    /**
-     * Returns true if the user needs to set an https_proxy environment variable
-     *
-     * This method can be removed after the transition period
-     */
-    public function needsTransitionWarning(): bool
-    {
-        return $this->needsTransitionWarning;
-    }
-
     /**
      * Returns a ProxyItem if one is set for the scheme, otherwise null
      */
@@ -116,15 +94,6 @@ class ProxyManager
         }
 
         if ($scheme === 'https') {
-            // this can be removed after the transition period
-            if ($this->isTransitional && $this->httpsProxy === null) {
-                if ($this->httpProxy !== null && !$this->ignoreHttpsProxy) {
-                    $this->needsTransitionWarning = true;
-
-                    return $this->httpProxy;
-                }
-            }
-
             return $this->httpsProxy;
         }
 
@@ -179,11 +148,6 @@ class ProxyManager
                 if ($_SERVER[$name] !== '') {
                     return [$_SERVER[$name], $name];
                 }
-                // this can be removed after the transition period
-                if ($this->isTransitional && strtolower($name) === 'https_proxy') {
-                    $this->ignoreHttpsProxy = true;
-                    break;
-                }
             }
         }
 
diff --git a/tests/Composer/Test/Util/Http/ProxyManagerTest.php b/tests/Composer/Test/Util/Http/ProxyManagerTest.php
index 80c88a844..04c756b48 100644
--- a/tests/Composer/Test/Util/Http/ProxyManagerTest.php
+++ b/tests/Composer/Test/Util/Http/ProxyManagerTest.php
@@ -20,11 +20,6 @@ use Composer\Test\TestCase;
  */
 class ProxyManagerTest extends TestCase
 {
-    // isTransitional can be removed after the transition period
-
-    /** @var bool */
-    private $isTransitional = true;
-
     protected function setUp(): void
     {
         unset(
@@ -142,31 +137,12 @@ class ProxyManagerTest extends TestCase
     public function testNoHttpsProxyDoesNotUseHttpProxy(): void
     {
         $_SERVER['http_proxy'] = 'http://proxy.com:80';
-
-        // This can be removed after the transition period.
-        // An empty https_proxy value prevents using any http_proxy
-        if ($this->isTransitional) {
-            $_SERVER['https_proxy'] = '';
-        }
-
         $proxyManager = ProxyManager::getInstance();
+
         $proxy = $proxyManager->getProxyForRequest('https://repo.org');
         self::assertSame('', $proxy->getStatus());
     }
 
-    /**
-     * This test can be removed after the transition period
-     */
-    public function testTransitional(): void
-    {
-        $_SERVER['http_proxy'] = 'http://proxy.com:80';
-        $proxyManager = ProxyManager::getInstance();
-
-        $proxy = $proxyManager->getProxyForRequest('https://repo.org');
-        self::assertSame('http://proxy.com:80', $proxy->getStatus());
-        self::assertTrue($proxyManager->needsTransitionWarning());
-    }
-
     /**
      * @dataProvider dataRequest
      *
diff --git a/tests/Composer/Test/Util/StreamContextFactoryTest.php b/tests/Composer/Test/Util/StreamContextFactoryTest.php
index d1fe5db31..bb89cefd5 100644
--- a/tests/Composer/Test/Util/StreamContextFactoryTest.php
+++ b/tests/Composer/Test/Util/StreamContextFactoryTest.php
@@ -133,7 +133,7 @@ class StreamContextFactoryTest extends TestCase
 
     public function testHttpProxyWithoutPort(): void
     {
-        $_SERVER['http_proxy'] = 'http://username:password@proxyserver.net';
+        $_SERVER['https_proxy'] = 'http://username:password@proxyserver.net';
 
         $context = StreamContextFactory::getContext('https://example.org', ['http' => ['method' => 'GET', 'header' => 'User-Agent: foo']]);
         $options = stream_context_get_options($context);
@@ -221,7 +221,7 @@ class StreamContextFactoryTest extends TestCase
 
     public function testInitOptionsDoesIncludeProxyAuthHeaders(): void
     {
-        $_SERVER['http_proxy'] = 'http://username:password@proxyserver.net:3128/';
+        $_SERVER['https_proxy'] = 'http://username:password@proxyserver.net:3128/';
 
         $options = [];
         $options = StreamContextFactory::initOptions('https://example.org', $options);