Wordpress Cannot re-assign auto-global variable

I have a plugin that was working until recently. One morning I woke up to my website being down.

I disabled the plugin and when I went to reactive it I had the following error:

Fatal error: Cannot re-assign auto-global variable _POST in ………./icalculator.php on line 213

Here’s the line 213 and a few following it. Any idea how to correct this?

function mm_iching_page($_POST) {
  $_SESSION['iching_result'] = serialize($_POST);
  foreach($_POST as $key => $value) {
    ${$key} = $value;
  }

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WordPress Cannot re-assign auto-global variable _POST