The only thing wrong is there is a flaw in a computerized audio/video sync check system, a completely useless feature. If the video as viewed on YouTube (or any other final delivery of choice) is in sync then there is no problem, if it’s out of sync then any editor will notice it and be able to quickly figure out at what point in the workflow the issue occurs, thus making an alert at any point rather useless.
Also, if the audio/video is out of sync it will be all audio that is effected, not just some tracks/clips. Thus there is no need to be concerned about subtle sound fx, music, etc being out of sync and slipping past QC. I will say that it’s generally wise to view your final video on several different browsers as each can have subtle differences with how they process video, but as long as it looks in sync across the main browsers you’re good.