Forms Success Redirect not working

Dear Divi Helpers,

Have you ever had issues with Form Success Redirect? Or simply with Form Success Messages?

For our 2 forms we have set up redirect to 2 different thank you pages (one in English and one in Italian). These thank you pages are really important for us as we are tracking conversions through them.

Everything worked and also conversion were tracked fine in google ads. Then something happened and suddenly they stopped working confusing a lot our users since also the success message is not appearing.

You can check yourself in the following links:
https://www.sailover.net/en/contacts/ (In this form the thank you page is still set up)
https://www.sailover.net/contatti/ (In this form I removed the redirect to the thank you page to verify if the general message would have appeared). Please note also that here right after I filled in all fields, rather than the success message, a weird copy appears just underneath the first field on top "Assicurati di riempire tutti i campi obbligatori" which means "please be sure to fill in all required field" - see this screenshot for references https://prnt.sc/ugyvwo

Please note we are receiving anyway users data each time the user is hitting the SEND button (thanks to a server set up) and unless some fields are missing also DIVI is sending us all data in the request.
As you can imagine this is good but we really need to have a good UX and to track conversions.

Any suggestion? Do you suggest to use another plugin for forms? Do you know any with both conditional rules and thank you pages redirect?

I am also contacting DIVI support but I am not sure they will be able to help.

Thank you very much in advance for your support.

Kind regards,

Roberta