diff --git a/yt_dlp/extractor/youtube.py b/yt_dlp/extractor/youtube.py
index 2b026ef05..e69373ba2 100644
--- a/yt_dlp/extractor/youtube.py
+++ b/yt_dlp/extractor/youtube.py
@@ -3280,7 +3280,7 @@ class YoutubeIE(YoutubeBaseInfoExtractor):
             except Exception as e:
                 raise JSInterpreter.Exception(traceback.format_exc(), cause=e)
 
-            if ret.startswith('enhanced_except_') or ret.endswith(f'_w8_{s}'):
+            if ret.startswith('enhanced_except_') or ret.endswith(s):
                 raise JSInterpreter.Exception('Signature function returned an exception')
             return ret