TYPO3 EXT:form afterSubmit hook per form definition

ext_localconf.php

<?php

$GLOBALS['TYPO3_CONF_VARS']['SC_OPTIONS']['ext/form']['afterSubmit'][\YourVendor\YourPackage\Form\StatisticsHook::class] = \YourVendor\YourPackage\Form\StatisticsHook::class;

StatisticHook.php

<?php

declare(strict_types=1);

namespace YourVendor\YourPackage\Form;

use TYPO3\CMS\Form\Domain\Model\Renderable\AbstractRenderable;
use TYPO3\CMS\Form\Domain\Model\Renderable\RenderableInterface;
use TYPO3\CMS\Form\Domain\Runtime\FormRuntime;

class StatisticsHook
{
    /**
     * @param FormRuntime        $formRuntime
     * @param AbstractRenderable $renderable
     * @param string|int         $elementValue
     * @param array<string|int>  $requestArguments
     *
     * @return string|int
     */
    public function afterSubmit(FormRuntime $formRuntime, RenderableInterface $renderable, $elementValue, array $requestArguments = [])
    {
        // The hook is not called for the form itself but for all children, therefore check for the page and get the parent renderable (the form)
        if ($renderable->getType() === 'Page' && !empty($renderable->getParentRenderable()->getRenderingOptions()['statistics'])) {
            $statisticSettings = $renderable->getParentRenderable()->getRenderingOptions()['statistics'];
            if ($statisticSettings['enable']) {
                // ... do what ever you like
                // Use `$requestArguments` to get the submitted values of the current step/page, as they are not processed yet
            }
        }

        // You must return the element value in any case, otherwise the submitted value is lost
        return $elementValue;
    }
}

yourFormIdentifier.form.yaml

renderingOptions:
    submitButtonLabel: Submit
    statistics:
        enable: true
    translation:
        translationFiles:
            100: '...'
    fluidAdditionalAttributes:
        novalidate:
type: Form
identifier: yourFormIdentifier
label: 'The form name or label'
prototypeName: standard
finishers:
    ...
renderables:
    ...