diff --git a/test/test_InfoExtractor.py b/test/test_InfoExtractor.py
index e0b1df9126..7c3825f779 100644
--- a/test/test_InfoExtractor.py
+++ b/test/test_InfoExtractor.py
@@ -1964,7 +1964,7 @@ def test_search_nextjs_v13_data(self):
             <script>(self.__next_f=self.__next_f||[]).push([0])</script>
             <script>self.__next_f.push([2,"0:[\"$\",\"$L0\",null,{\"do_not_add_this\":\"fail\"}]\n"])</script>
             <script>self.__next_f.push([1,"1:I[46975,[],\"HTTPAccessFallbackBoundary\"]\n2:I[32630,[\"8183\",\"static/chunks/8183-768193f6a9e33cdd.js\"]]\n"])</script>
-            <script nonce="abc123">self.__next_f.push([1,"e:[false,[\"$\",\"div\",null,{\"children\":[\"$\",\"$L18\",null,{\"foo\":\"bar\"}]}],false]\n"])</script>
+            <script nonce="abc123">self.__next_f.push([1,"e:[false,[\"$\",\"div\",null,{\"children\":[\"$\",\"$L18\",null,{\"foo\":\"bar\"}]}],false]\n    "])</script>
             <script>self.__next_f.push([1,"2a:[[\"$\",\"div\",null,{\"className\":\"flex flex-col\",\"children\":[]}],[\"$\",\"$L16\",null,{\"meta\":{\"dateCreated\":1730489700,\"uuid\":\"40cac41d-8d29-4ef5-aa11-75047b9f0907\"}}]]\n"])</script>
             <script>self.__next_f.push([1,"df:[\"$undefined\",[\"$\",\"div\",null,{\"children\":[\"$\",\"$L17\",null,{}],\"do_not_include_this_field\":\"fail\"}],[\"$\",\"div\",null,{\"children\":[[\"$\",\"$L19\",null,{\"duplicated_field_name\":{\"x\":1}}],[\"$\",\"$L20\",null,{\"duplicated_field_name\":{\"y\":2}}]]}],\"$undefined\"]\n"])</script>
             <script>self.__next_f.push([3,"MzM6WyIkIiwiJEwzMiIsbnVsbCx7ImRlY29kZWQiOiJzdWNjZXNzIn1d"])</script>
diff --git a/yt_dlp/extractor/common.py b/yt_dlp/extractor/common.py
index 3cd0dfa36b..c85949c3c6 100644
--- a/yt_dlp/extractor/common.py
+++ b/yt_dlp/extractor/common.py
@@ -1824,7 +1824,7 @@ def flatten(flight_data):
 
         for f in flight_text.splitlines():
             prefix, _, body = f.partition(':')
-            if body.startswith('[') and body.endswith(']') and re.fullmatch(r'[0-9a-f]{1,3}', prefix):
+            if body.startswith('[') and body.endswith(']') and re.fullmatch(r'[0-9a-f]{1,3}', prefix.strip()):
                 # The body isn't necessarily valid JSON, so this should always be non-fatal
                 flatten(self._parse_json(body, video_id, fatal=False, errnote=False))