SSH - Getting 'Broken pipe' error when trying to configure multi-hop connection

I have two SSH servers: ServerA that supports key-based authentication, and is accessible from my workstation, and ServerB that only supports password-based auth, and can only be accessed from ServerA. My goal is to SSH into ServerB from my workstation, but I'm getting a very useless error. Here's my ~/.ssh/config file:

Host ServerA
    HostName 10.8.0.1
    User ubuntu
    Port 22
    IdentityFile ~\.ssh\id_server_a.pem

Host ServerB
    ServerAliveInterval 120
    HostName 12.34.56.78
    User myuser
    Port 12221
    ProxyCommand ssh -W %h:%p ServerA

This should work, but when I type in the command ssh ServerB, I get the following error:

/bin/sh: No such file or directory
banner exchange: Connection to UNKNOWN port 65535: Broken pipe

I have tested both SSH connections, as in I'm able to explicitly connect to ServerA with the key, and from ServerA's shell I'm able to connect to ServerB with the port, username and password.

Where does this error originate from (Workstation, ServerA or ServerB) and is there anything I can do to fix it?

If the client system is a Mac - a Ventura upgrade is likely the cause.

Based on the timing of the OP's question, that seems quite plausible.
Upgrading my Mac to Ventura (MacOS 13.4) broke ssh for me, giving me a very similar error:

Infinite reexec detected; aborting
banner exchange: Connection to UNKNOWN port 65535: Broken pipe

One significant caveat - I'm using a PIV (smartcard) to authenticate

After troubleshooting with IT support the solution turned out to be:

1. Remove / comment out the PKCS11Provider line in your ~/.ssh/config
2. Run the following commands:

   ssh-add -e /usr/lib/ssh-keychain.dylib
     #Note - above command may produce the error:  
     #   'Could not remove card "/usr/lib/ssh-keychain.dylib": agent refused operation'
     #This can be ignored; the file simply has no items to remove
   ssh-add -D
   killall -9 ssh-agent
   ssh-add -s /usr/lib/ssh-keychain.dylib
   

3. You should now be able to ssh

_{Note: If ssh still fails - The killall should have cleared all cached ssh process/keys/etc. A reboot will definitely clear any cached data that may be interfering.}