PHP issue

Hello

I have the following issue on my website:

Message

Notice add_submenu_page was called incorrectly. The seventh parameter passed to add_submenu_page() should be an integer representing menu position. Please see Debugging in WordPress for more information. (This message was added in version 5.3.0.)
Location 1 –
wp-includes/functions.php:4903
add_submenu_page()
wp-content/plugins/flo-forms/admin/class-flo-forms-admin.php:446
Flo_Forms_Admin->flo_add_forms_options()
wp-includes/class-wp-hook.php:288
do_action(‘admin_menu’)
wp-admin/includes/menu.php:155
Plugin: flo-forms

Can I please get any info on what that could be?

The page I need help with: [log in to see the link]