The feeling of water in LZ dream is fear, so it implies difficulties and loss of interests.
Among them, LZ's fear of water is not so much a fear of not knowing water as a reflection of LZ's lack of confidence in some things in reality.
The whole scene implies that LZ is now surrounded by such difficulties and self-distrust.
The appearance of mother in the dream implies what LZ relies on and hopes, and her disappearance means that LZ can't see hope and dependence in reality, suggesting that she can't get help from others.
Panic-stricken destruction implies that this is the case in reality, so on the contrary, LZ should be calm, don't panic, don't lose his mind, don't distrust himself, and be calm, calm and cautious in reality.