Bethesda banned players who snuck into Fallout 76's 'dev room' last month (opens in new tab)—so it's no wonder one player that accidentally accessed the sealed Vault 63 this weekend was worried about the developer taking action against their account. So far they haven't been punished, and they managed to grab plenty of photos from inside the vault before fast travelling out.
The player, posting on McStaken on Reddit, said the game warped them into the vault during a Rad-Rat Horde event. Other players in the Reddit thread (opens in new tab) have been through the same thing, with the game spawning them inside the vault at the start of an event, and the only way to leave is to fast travel out. McStaken is worried about being banned, so they've submitted a support ticket to Bethesda telling the developer what happened.
Vault 63 is sealed in Fallout 76: there's a keycard slot next to the entrance, but nobody has been able to get in legitimately. Players have been able to enter by purposefully glitching inside, and they've also gained access to other sealed vaults, such as 96 and 94.
McStaken took various images inside the vault, including one that suggests it leads into a mine. They also found what they believed to be a nuclear reactor, alongside a skeleton with a Vault 63 jumpsuit. You can see a couple of the images below, or view them all in the thread (opens in new tab).