indignantdenial
978
Not very old!
He bought it in October 2020, and published his video with this account in April 2023, so it certainly was before April 2023, seeing as Lange servicing is lengthy and he has the watch back—repaired. Rubber gaskets do not fail without either encountering significant chemical wear or if mounted improperly. Generally speaking, they shouldn't fail as part of a dress watch either—such a watch is not subject to serious wearing conditions that might reasonably impact their performance, unlike my Sinn EZM 13.1, which I have taken out in +35ºC heat and -32ºC cold (where the watch is actually exposed to these temperatures, it isn't underneath clothing); its WR has remained steadily at the 500m rating from the factory (I have had it checked). It could be possible Lange QC failed, as you say, but that would be a pretty miserable failure and indicative of very sloppy work if the case (it's really not that hard to test WR properly).
In any case, when I see 30m WR, I assume the figure is worthless unless the company warrants the watch can actually be submerged and remain safe. If that is the case, as with Patek, Omega, etc. then I think it is meaningful—otherwise, it's, as Watch Enthusiast London says, a "trade misdescription".