I think I've discovered the problem. The canonical tag (<link rel="canonical" href="/https://scuola-lavoro.it/event-manager/wp-admin/admin-ajax.php">) points to the event-manager page which however does not exist on my site. Instead, it probably existed in a previous site http://scuola-lavoro.it (note non-https domain) which was subsequently abandoned. The proof is in the last line of this page: https://yellow.place/it/scuola-lavoro-it-padua-italy, found as a referral. At this point the wordpress invoice wp-admin is also explained. I apologize for the inconvenience and thank you if someone could show me how to proceed.

Hi there,

Thanks for contacting us. Sorry for the inconvenience. You should clean your wordpress files & database first. Then check again.

-Thanks

Sorry but I was not understood. I use Joomla4, not Wordpress.

If you look this url. You will see the wp-admin inside the url. The wp-admin comes from WordPress.

https://scuola-lavoro.it/event-manager/wp-admin/admin-ajax.php?action=spiderbigcalendar_week_widget&theme_id=1&calendar=1&select=month,&months=03,04,05&date=1991-04-17&many_sp_calendar=1&cat_id&widget=1&TB_iframe=1

Forgive me but you should read well. I don't use and have never used Wordpress. I don't have Wordpress files on my site. I know wp-admin is from Wordpress. But I don't understand how it can be in my url. That's all.

But I don't understand how it can be in my url.

We didn't change anything on your site.