Hi @BioLogIn,
Your domain fighting.ru and subdomain www.fighting.ru are advertising AAAA records and Let’s Encrypt prefers IPv6 over IPv4 so it will try to validate them using the IPv6 record but your system/web server is not configured properly so it gets a 404 error message.
You should fix your system/web server config to serve the same content using IPv4 and IPv6 or remove the AAAA records for fighting.ru and www.fighting.ru.
Cheers,
sahsanu