Lightning Network `channel_update` message Flag clarification
The flags field (2 bytes) has been split into two different (1 byte) fields, the message_flags (most significant bits) and the channel_flags field (least significant bits). Hence the flags value displayed in lnd has the message_flags byte set to 0x00 and the message_flags set to 0x01.

message_flags indicates that this channel_update has some optional fields appended to the end. In this case it has the 0th bit set, which corresponds to the option_channel_htlc_max option, hence the channel_update has an additional field htlc_maximum_msat appended.