diff --git a/news/8711.removal.rst b/news/8711.removal.rst
new file mode 100644
index 00000000000..80423aa4259
--- /dev/null
+++ b/news/8711.removal.rst
@@ -0,0 +1 @@
+Un-deprecate source distribution re-installation behaviour.
diff --git a/src/pip/_internal/resolution/resolvelib/resolver.py b/src/pip/_internal/resolution/resolvelib/resolver.py
index f89afaf433c..12f96702024 100644
--- a/src/pip/_internal/resolution/resolvelib/resolver.py
+++ b/src/pip/_internal/resolution/resolvelib/resolver.py
@@ -19,8 +19,6 @@
     PipDebuggingReporter,
     PipReporter,
 )
-from pip._internal.utils.deprecation import deprecated
-from pip._internal.utils.filetypes import is_archive_file
 
 from .base import Candidate, Requirement
 from .factory import Factory
@@ -136,25 +134,6 @@ def resolve(
                     )
                     continue
 
-                looks_like_sdist = (
-                    is_archive_file(candidate.source_link.file_path)
-                    and candidate.source_link.ext != ".zip"
-                )
-                if looks_like_sdist:
-                    # is a local sdist -- show a deprecation warning!
-                    reason = (
-                        "Source distribution is being reinstalled despite an "
-                        "installed package having the same name and version as "
-                        "the installed package."
-                    )
-                    replacement = "use --force-reinstall"
-                    deprecated(
-                        reason=reason,
-                        replacement=replacement,
-                        gone_in="21.3",
-                        issue=8711,
-                    )
-
                 # is a local sdist or path -- reinstall
                 ireq.should_reinstall = True
             else:
diff --git a/tests/functional/test_new_resolver.py b/tests/functional/test_new_resolver.py
index 052c001791b..26e0886f1ed 100644
--- a/tests/functional/test_new_resolver.py
+++ b/tests/functional/test_new_resolver.py
@@ -1228,7 +1228,6 @@ def test_new_resolver_does_reinstall_local_sdists(script):
         expect_stderr=True,
     )
     assert "Installing collected packages: pkg" in result.stdout, str(result)
-    assert "DEPRECATION" in result.stderr, str(result)
     script.assert_installed(pkg="1.0")