diff --git a/yt_dlp/extractor/common.py b/yt_dlp/extractor/common.py
index 9829aee81c..d601e17514 100644
--- a/yt_dlp/extractor/common.py
+++ b/yt_dlp/extractor/common.py
@@ -1797,7 +1797,7 @@ def flatten(flight_data):
                 if not isinstance(data, dict):
                     return
                 children = data.pop('children', None)
-                if data and isinstance(name, str) and name.startswith('$L'):
+                if data and isinstance(name, str) and re.fullmatch(r'\$L[0-9a-f]+', name):
                     # It is useful hydration JSON data
                     nextjs_data[name[2:]] = data
                 flatten(children)