does database chunk() have a memory leak?

In laravel, I have a query that searches thousands of rows in a database, and I trying to compile that into a CSV file. In attempt to reduce memory usage, I get 500 rows at a time and output the CSV.

    $callback = function () use ($query) {
      $file = fopen('php://output', 'w');

      $query->chunk(500, function ($rows) use ($file) {
        foreach ($rows as $key => $row) {
          fputcsv($file, array_map(...$rows...));
        }
        log_info("Memory used " . memory_get_usage());
      });

      fclose($file);
    };

    $headers = [ ... ];

    return response()->stream($callback, 200, $headers);

The actual query is a bit more complex, and involves getting related models which also need to be rehydrated. When I run this, it begins generating the CSV file and, after a while, runs out of memory. This is in my log

(59): Memory used 17208328;
(59): Memory used 25105328;
(59): Memory used 30601328;
...
(59): Memory used 127380496;
(59): Memory used 129352584;
(59): Memory used 131207672;
[2025-11-23 23:50:15] qa.ERROR: Allowed memory size of 134217728 bytes exhausted (tried to allocate 16384 bytes) 

What I Tried

I tried putting the following inside the chunk loop, hoping that it would free memory. It had no effect on the memory consumption.

        unset($rows);
        flush();
        gc_collect_cycles();