i think this one has been around for a while, maybe not
but it's really been annoying me lately!

here are the symptoms.
if you have a linked stereo clip in the timeline
and you overwrite the VIDEO only, the stereo audio becomes 2tk mono.

it only happens when you COMPLETELY overwrite a linked video clip.

you can overwrite by making an edit,
doing an extend edit in the timeline,
or moving a video clip in the timeline over an existing video with linked audio.

since these are things you do regularly while editing i'd say this is a problem!
being able to move clips around freely in the timeline, without worrying about the consequences is pretty important.