Hi neotrope,
thank you for your answers!
I try all your suggestion, I didn’t finda anything strange in htaccess and in wp-config.php, no other file or directory with “index” name, but I’m not an expert programmer, only a self taught site creator.
Now I try another way, I disabled Yoast Sitemap generation and I install google xml sitemap plugin. It identifies correctly the site map dir “https://www.vicoter.it/index.php?xml_sitemap=params=” and I tried to give it to google webmaster.
What do you think about this?
Thank you,
Best regards,
Edoardo