The error says that the item_id word in that code is being seen as a constant and not a variable. While the code snippet is useful, it doesn't tell us much without the backtrace to find out the location of the code that is causing the fatal error. I run Formidable every day in my development environment built with PHP/8.2.1 and Formidable has no problems. Even though I doubt it's a problem with Formidable and more likely some custom code snippet, are you on the latest version of Formidable? What code is causing the problem? You should be able to see a backtrace in you server's PHP error log.

This is the code snippet (old). Where did I do wrong? I am totally blind. xD  I believe this is the code that causes the issue, where item_id is not defined-the last line. ([STDERR] PHP Fatal error:  Uncaught Error: Undefined constant "item_id" in /home/elightin/domains/elearnready.app/public_html/wp-content/themes/woodmart-one/single-class-profile.php:106)

$entry_table = $wpdb->prefix."frm_item_metas";
$entry_ids = $wpdb->get_results ( "SELECT item_id FROM $entry_table WHERE meta_value ='$sid' and field_id = '9'");
$entry_ids = json_decode(json_encode($entry_ids), True);
$x = count($entry_ids) - 1;
$entry = array();
for($i = $x; $i >= 0; $i--)
{
	$entry = FrmProEntriesController::show_entry_shortcode(array( 'id' => $entry_ids[$i][item_id], 'format' => 'array'));
}