It’s intentional. The general idea is to make it easier to detect fraudulently issued certificates. LetsEncrypt submit all certificates[0] to Certificate Transparency[1] logs.

Chrome won’t actually show the green address bar for EV certs unless a CT proof is provided along with the certificate[2].

[0]https://letsencrypt.org/certificates/

[1]https://www.certificate-transparency.org/faq

[2]https://blog.digicert.com/certificate-transparency-required-...

Certificate transparency makes it much harder to surreptitiously issue a certificate and holds the offending CA responsible in case of unauthorized certificates. If your site is not public, you're better off with your own private CA anyway.

It's the public certificate audit log. It's not an accidental data leak.

For private sites just use your own CA.

Also the server for LetsEncrypt is open source [1] and comes with test scripts to run it during development and testing to avoid premature exposure to the public instance of LetsEncrypt.

[1] https://github.com/letsencrypt/boulder

https://whois.domaintools.com/crt.sh Thought I recognised the favicon, it's Comodo. I don't see the problem, if you want a secret url then self sign and distribute your certificate with other methods.