ERR_NGROK_SHIP_ENDPOINT_URL_PRIVATE_HOSTNAME_LABEL_LIMIT_EXCEEDED: The FIELD hostname HOST has too many labels - ngrok documentation

What does ERR_NGROK_SHIP_ENDPOINT_URL_PRIVATE_HOSTNAME_LABEL_LIMIT_EXCEEDED mean?

ngrok returns ERR_NGROK_SHIP_ENDPOINT_URL_PRIVATE_HOSTNAME_LABEL_LIMIT_EXCEEDED with this message:

The <FIELD> hostname <HOST> has too many labels. Max <LIMIT> under this private suffix, got <GOT>. Use hyphens instead of dots.

Where can I get more help with ERR_NGROK_SHIP_ENDPOINT_URL_PRIVATE_HOSTNAME_LABEL_LIMIT_EXCEEDED?

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