Well spotted! Net::Telnet suggests:
in reply to Re: Perl Telnet client not receiving all the data
in thread Perl Telnet client not receiving all the data
Usually you want the remote TERM environment variable to be set to something like "dumb" so you don't read escape sequences meant to be interpreted by a display terminal.
However, here the server requests neither terminal type, nor environment variables, but sends a "\033Z" to query terminal device attributes. A good response to this might be "\033[?6c" ('I am a vt102').