ERR_NGROK_SHIP_POOL_LAMBDA_SSH_KEY_REFUSED: Lambda Cloud refused the SSH key (HTTP STATUS): REASON - ngrok documentation

What does ERR_NGROK_SHIP_POOL_LAMBDA_SSH_KEY_REFUSED mean?

ngrok returns ERR_NGROK_SHIP_POOL_LAMBDA_SSH_KEY_REFUSED with this message:

Lambda Cloud refused the SSH key (HTTP <STATUS>): <REASON>

Where can I get more help with ERR_NGROK_SHIP_POOL_LAMBDA_SSH_KEY_REFUSED?

Email support@ngrok.com and include the error code.