
Spoiler
Of course, there must be a very good, secret, and dangerous reason why Jinshi's pretending that he's a eunuch. If Mao ever confirms that he's not a eunuch before he reveals it himself, Jinshi would be put in a difficult position of either protecting Mao or silencing her. So he's mad bec Mao is kinda pushing it too far, and he had no choice but to drink the tea to make a "show" that he's not worried about infertility.

This is also just a speculation but I think Jinshi is the son of the current emperor. I remember the current emperor's concubine, Jinshi mom who is Lady Aduo and the empress were giving birth at the same time. And they switched babies LOL.
Im pretty damn sure that he is the son and is currently overlooking the palace for his dad lol.
Can someone give me spoilers?