The vulnerability description states that large headline prefixes (e.g., <h9999999>) cause memory consumption. The provided commit 959561879693bf4a576f99c6733b50b01186aa08 directly addresses this issue. The diff for markdownify/__init__.py shows modifications within the convert_hn method of the MarkdownConverter class. Specifically, a line n = max(1, min(6, n)) was added. This line sanitizes the input n (the heading level), which was previously used without validation. Therefore, convert_hn is the function that processed the unsanitized, potentially very large heading level, making it the vulnerable function prior to this patch. The full name as it would appear in a profiler would include the class and module, hence markdownify.MarkdownConverter.convert_hn.