Error 500 after installing Related Articles with PHP 8

Hi, I have checked it but it seems without much success as you can see here: www.seo-suedwest.kunde-formativ.net/8465...und-23-november.html.
The version of the plugin that I am using on my live website and that is working is 1.7.1. Perhaps that helps.

In the attachment you can see the settings option I need.

Regards

A question regarding that: Do we have to install the plugin / module after the change again? I could see that after the change the module was deactivated and no Thumbnails were shown any more.

Hi, we have implemented the other code, but it still does not work as expected. I will show you an example. Please take the article on the test site with the new plugin which you can find here: www.seo-suedwest.kunde-formativ.net/8465...und-23-november.html
The same article is on the live site: www.seo-suedwest.de/8465-anzeichen-fuer-...und-23-november.html
If you look at the shown related articles, you can see that on the test site with the new plugin old related articles are shown. On the live website with the old plugin new articles appear as related articles. This is how it's supposed to work.
On the test site the thumbnails are missing after the change.
Regards