which is still there if you are not using lets encrypt, because they can strongarm them to make a fake cert for your domain, and install a proxy repackaging HTTPS traffic with the fake certificate. all browsers trust the lets encrypt root certificate, so they won't see anything suspicious.

the only thing there today to detect this (but not avoid) is certificate transparency logs. all modern certificates are required to be added to this log, for the CA to remain compliant. but browsers are not checking the logs, that would be a lot of additional traffic and how do they decide if a certificate was created maliciously? also, lets encrypt could afford being noncompliant, browser vendors can't realistically just distrust their root certificate, many sites would become inaccessible.

Edit: no, it doesn't. Looking at the comments below, it's public key crypto.

Original comment:

The problem is that if that is your threat model, then the VPS provider, ISP, and literally everything between you and letsencrypt can pull a conpromised key fro letsencrypt.

This actually happened btw, an xmpp server was attacked this way, they compromised not the server itself, but the VPS provider MITMed their traffic: https://www.devever.net/~hl/xmpp-incident

If your threat model involves this, then the only solution is Tor, which eliminates these requirements of trust.

Yep, that's what I described and any CA accepted by the client can do it