I'll take that as the date and time are correct.
You might have the program ts installed (from the moreutils package), in which case you could pipe all the output through that. E.g.
30 2 * * * /usr/bin/certbot renew 2>&1 | ts >> /var/log/lets-encrypt/poriburano.it_renew.log
Certbot also probably keeps its own logs in /var/log/letsencrypt (no hyphen), even if you don't ask it to do so. Those might have additional relevant information about what it's doing or not doing.
Thanks..Thank you for your support..I'll update you