Aside from ensuring his own safety and avoiding disturbances, Fang Mu also didn't want his Life-bound Beastmaster's Blood of Abundance to be exposed to others, not even to his guardian.
To keep a secret, some things are best left known only to oneself, not even to the gods in the shadows!
Lian Dai's perception was acutely sensitive. She picked up on the strange changes in Fang Mu and asked him concernedly,
"Little Wood, is there something wrong with your body?"
Lian Dai knew Fang Mu had previously been keenly interested in pollutants and was deeply fearful that the unusual state of Fang Mu's body had something to do with them.
If it truly was due to contaminants, the consequences could very well be irreversible.
Lian Dai had heard many tales of human prodigies meeting their downfall due to exposure to pollutants, causing their innate talents to be utterly ruined, transforming them into something neither human nor ghost.