diff --git a/scrapy/core/downloader/contextfactory.py b/scrapy/core/downloader/contextfactory.py
index a934cbbc7..f09f5a919 100644
--- a/scrapy/core/downloader/contextfactory.py
+++ b/scrapy/core/downloader/contextfactory.py
@@ -120,8 +120,13 @@ class _ScrapyClientContextFactory(BrowserLikePolicyForHTTPS):
     def _get_cert_options_kwargs(self) -> dict[str, Any]:
         kwargs: dict[str, Any] = {
             "fixBrokenPeers": True,
-            "acceptableCiphers": self.tls_ciphers,
         }
+        # Pass acceptableCiphers to Twisted only when explicitly set.
+        # When None (user set DOWNLOADER_CLIENT_TLS_CIPHERS=None),
+        # omit the kwarg so Twisted uses its own curated cipher list
+        # instead of falling back to OpenSSL's DEFAULT.
+        if self.tls_ciphers is not None:
+            kwargs["acceptableCiphers"] = self.tls_ciphers
         if self.tls_min_version or self.tls_max_version:
             kwargs.update(
                 _get_cert_options_version_kwargs(
diff --git a/scrapy/core/downloader/tls.py b/scrapy/core/downloader/tls.py
index c5cf1156d..6433365ba 100644
--- a/scrapy/core/downloader/tls.py
+++ b/scrapy/core/downloader/tls.py
@@ -43,13 +43,6 @@ _openssl_methods: dict[str, int] = {
 
 
 def __getattr__(name: str) -> Any:
-    if name == "DEFAULT_CIPHERS":
-        warnings.warn(
-            "scrapy.core.downloader.tls.DEFAULT_CIPHERS is deprecated.",
-            ScrapyDeprecationWarning,
-            stacklevel=2,
-        )
-        return AcceptableCiphers.fromOpenSSLCipherString("DEFAULT")
     deprecated = {
         "METHOD_TLS": "TLS",
         "METHOD_TLSv10": "TLSv1.0",
diff --git a/tests/test_core_downloader.py b/tests/test_core_downloader.py
index fdd5edc27..e87a08b36 100644
--- a/tests/test_core_downloader.py
+++ b/tests/test_core_downloader.py
@@ -215,11 +215,13 @@ class TestContextFactoryCiphers(TestContextFactoryBase):
 
     @coroutine_test
     async def test_none(self, server_url: str) -> None:
-        """A None value enables the Twisted default ciphers."""
+        """When DOWNLOADER_CLIENT_TLS_CIPHERS=None, acceptableCiphers is
+        not passed to CertificateOptions, so Twisted uses its own curated
+        cipher list instead of falling back to OpenSSL DEFAULT."""
         crawler = get_crawler(settings_dict={"DOWNLOADER_CLIENT_TLS_CIPHERS": None})
         factory = build_from_crawler(_ScrapyClientContextFactory, crawler)
         assert factory.tls_ciphers is None
-        assert factory._get_cert_options_kwargs()["acceptableCiphers"] is None
+        assert "acceptableCiphers" not in factory._get_cert_options_kwargs()
         await self._assert_factory_works(server_url, factory)