Normally, chat traffic is packetized to ensure that what the sender really said is received perfectly at the receiver.  If a data path is enabled to receive Raw Text then anything that isn't packetized (or was received incomplete) is displayed, but with a yellow background to alert you that it's not confirmed.

It is normal to receive garbage or partial transmissions, depending on RF propagation issues, and this will be displayed in yellow.  It can sometime indicate a bad serial cable, poor signal strength of the sender, receiver, or repeater.

If you wish to not see this "broken" data, you can disable the Raw Text option on a given data path in the Radio section of the Preferences.