After you upgrade to ESXi 7.0 Update 3d, SSH access might fail with one of the following symptoms:
Issue 1 :-  

• If "AcceptEnv" option is enabled in /etc/ssh/sshd_config, then SSH access might fail due SSHD process does not start, and you see no response when connecting on the ESXi host. See the resolution section to remove this option.

• If any of SSH client uses SHA-1 hash algorithm for example the ssh-rsa HostKeyAlgorithm, then SSH connection to ESXi server will fail. OpenSSH8.8 release note listed this as in Open SSH Release notes 

• This is due to OpenSSH upgrade to version 8.8 to fix security vulnerability 
• Product Support Notice was provided in the vSphere 7.0 Update 2 release, please refer the link vSphere 7.0 Update 2 release notes 

• Log on the ESXi host via DCUI 
• Execute the below command 
  • vi /etc/ssh/sshd_config
  • Comment / Remove the option "AcceptEnv"
  • Save and exit using command ":wq!"
  • Restart SSH service 
    • /etc/init.d/SSH restart

• Option 1 :- Preferred workaround is to use latest version of the SSH client 
• Option 2 :- Add the ssh-rsa host key type to the HostKeyAlgorithms line of the configuration file or preferably a more secure key type such as ecdsa or rsa-sha2.