diff --git a/src/pip/_internal/cli/req_command.py b/src/pip/_internal/cli/req_command.py
index dbd15cbce63..1607c78b187 100644
--- a/src/pip/_internal/cli/req_command.py
+++ b/src/pip/_internal/cli/req_command.py
@@ -276,6 +276,13 @@ def make_requirement_preparer(
                 gone_in="22.1",
             )
 
+        if options.progress_bar not in {"on", "off"}:
+            deprecated(
+                reason="Custom progress bar styles are deprecated",
+                replacement="to use the default progress bar style.",
+                gone_in="22.1",
+            )
+
         return RequirementPreparer(
             build_dir=temp_build_dir_path,
             src_dir=options.src_dir,