The defaults are far from the best settings, even the devs intended -q 0 to be the best setting, not the default -q 3, you can check this in their documentation, and both options even when intended to be among the best, are actually the worst, this is a LAME bug the developers clearly did not test at all.
This could be the reason this guy complained here and no one could solve his problem:
This is a vert well documented bug by now, here is another guy who noticed it:
https://hydrogenaudio.org/index.php/topic,125216.0.html
The default LAME settings are the worst at any bitrate, tested on as low as 8kbps all the way through to 320kbps, the only thing that changes is the cutoff point where the artifacts can be noticed, they eat up this frequencies at the top and surpress them making a muddy mess MP3 has always been know for, which does not have to be like that because with the patch the result is far better, even if not with the patch, setting exports to -q 4 already makes a very big improvement which disables the frequency eating algorithm.
This might not be noticed at 320kbps but MP3 is not intended to be a 320kbps only audio format, if lower kbps is required the change would make lower bitrate exports sound better, and 320kbps exports would be of higher fidelity as they would not be affected at all by this upper frequencies surpressing algorithm that muddies and makes noise artifacts at the upper frequency content of the file.