Although this issue currently seems confined to Chinese Genshin Impact players, the international player base has been cautioned against joining “any stranger’s co-op room” until the bug is resolved.
Examples shared on Reddit demonstrate the severity of the problem. In one comparison, an unaffected player sees a cannon and an electro tree, while the supposedly hacked player experiences an empty space in-game. In another instance, a geo pillar has vanished entirely from the game.