New maintenance work has been announced for Fallout 76. On February 14, the servers will be temporarily unavailable in the afternoon. Bethesda plans to remove items that have been duplicated by dupers.
The servers will be offline during this time: Maintenance work will begin at 3 PM. It is currently unclear how long the servers will be unavailable.
The maintenance work is addressing an issue with item duplication (Duping). We summarize the changes that Bethesda will implement.

Your items could soon disappear from your inventory
This is what the server maintenance is supposed to achieve: According to Bethesda, during the maintenance, a large list of items created through an exploit will primarily be removed.
This exploit is also known as Duping. Players manage to duplicate all kinds of items repeatedly through various tricks. This can range from harmless food items to legendary weapons. Bethesda attempted to respond to the item dupers with bans.
These items are often gifted to other players, sometimes sold for real money. Therefore, the in-game economy of Fallout 76 is quite damaged. Proven players are banned for duplication; at times, even players who merely possessed these items were affected.

A patch was supposed to stop this problem, but even after the update, Duping is still possible.
Is anything else happening during the maintenance? In addition to removing duplicated items, a server-side fix is also planned to reduce connection losses.
You can find the official announcement in the official Bethesda forum.
Players can not only become unwilling victims of duping items.
They can also accidentally enter areas that have not yet been unlocked.