I’m hesitant to call this a bug and post this in bug report section, to me this is looks like inconsistency in project management. This a building game, structures placement requirements are incredibly important. It might be fine in PvE environment, but in PvP it creates countless loopholes.
Why majority of objects can be placed under water? One exceptional category here is crafting stations, almost everything else can be placed even on bottom of the sea. You can even place fireplace underwater.
Notable example here are chests and vaults. If underwater chests are not that strong. Vaults are incredibly strong on its own, placing them under water just makes them even stronger. In PvP vaults are used as stand alone raid base, or you can just place a dozen of them in your base as decoy. They are cheap, have no downsides and you can spam them as much as you want.
Now to stuff that caused so much trouble, several decorations have inadequate placement requirements. I’ve counted 5 of them, everything is a dlc content. I don’t own preorder content and the anniversary dlc, so there is more of it. I just can’t test it.
This is just a minor inconsistency, but it went badly in PvP environment.