That's one level of security, but even for DoH, it's possible for entities to attack and control an HTTPS server, returning falsified DNS queries, and now the antigovernment.com website you logged in to talk about anti-government politics is actually run by government. The only way to prevent that is via DNSsec to make sure that antigovernment.com goes to a real antigovernment.com server.
If the government can transparently MITM your HTTPS connections with the DoH server, they can just as well MITM your connection to the real antigovernment.com server regardless of what DNS you use. And in fact, if they can't MITM your connection to the real antigovernment.com, they also can't trick you to talk to their fake antigovernment.com regardless of intercepting your DNS: you will connect to the attacker IP, the attacker IP will give you a bogus certificate, your browser will refuse to connect.
They only need a certificate signed by an authority trusted by your resolver. And, unlike for the website itself, your browser does not show certificate information for the DoH server.
DoH also does not solve the problem of where the DNS server you use gets its information from: A government can compromise the other side as well.
