Im guessing the panel here knows the timeline and the backstory to the letter, just havent read the specifics in the letter itself for themselves. Im also guessing this is why the FBI will never produce it.
There is a round of political poker underway, with the FBI and DOJ at risk of a major embarrassment and tactical defeat if Comer produces more in the way of public information than they do. Thus the FBI and DOJ may produce more than Comer currently has. Or, if they produce nothing or too little, their lack of bad faith diminishes the rational in future controversies for giving them time and deference in meeting demands for information.