^Firmware is a type of software that is saved on a read only chip in your machine. It tells the dvd drive how to recognize the various types of disks you might use in it, whether that might be a music cd, dvd movie, or blank media of various kinds. It will also contain a list of known types of blank media and set a specific type of strategy to burn each one.
If you put in a disk it cannot recognize, usually because it has a new id code not found in the current firmware, then the machine may try to burn the disk using a generic strategy. These generic burning strategies sometimes work, but often produce poor burns, or even failed burns.
Firmware updates should be available at the Panasonic website for your particular recorder. Look for instructions on how to flash a new firmware while at their site, or read in the manual for your recorder.