don't worry about Cisco deprecating things

my $telnet = Net::Telnet::Cisco->new($Host =>$ip)
my $cmd = "show tech-support";

my $matchop = qr/(?mx:^% Unknown VPN
	|^%IP routing table VRF.* does not exist. Create first$
	|^%No CEF interface information
	|^%No matching route to delete$
	|^%Not all config may be removed and may reappear after reactivating
	|^% ?This CLI is deprecated
)/;
 
my $bool_ret = $telnet->warnings($matchop);

# ....
@lines = $telnet->cmd( String => $cmd, Timeout => 90 );