Why is the emperor angry when he is treading on thin ice?

Because the emperor doesn't like gifts given in May.

In episode 22, the attendants sent in May brought two Haidongqing, but they didn't want both Haidongqing to be dying. They satirized the emperor as a "dying eagle".

The emperor was so angry that he broke up with Mei and his son without even giving him a chance to explain.

The result of this matter:

Because of this incident, Mei's imperial dream was completely shattered and she fell ill.

Many people think that it is in his best interest for the May 4th Movement to be responsible for this incident. You can kill Mei in one fell swoop, or you can take back all the power of Mei in recent years.

And even if the sunrise thinks so, it makes May 14 extremely angry, which he can't explain. In the end, the matter went away and no real frame-up was found.