In order to get the economic compensation for demotion and salary reduction, don't sign the examination without approval. Go to the Labor Arbitration Commission of High-tech Zone (it seems that the intersection of Jiankang East Street and Guangjin Road can have a specific address of Baidu) to apply for arbitration, even if you don't leave your job. Sometimes it is difficult for them to tell you that you have to leave your job before you can apply for arbitration. When arbitration is initiated, evidence of disapproval of salary reduction, such as labor contract, bank salary, email or chat records or audio, can be provided. After the application, if the company asks to resign, it will not do so until the arbitration result comes out, or if there is, it should not write personal reasons. If you leave your job, you should keep relevant evidence or consult a lawyer to send a letter to the company stating that the labor contract is terminated because of salary reduction. After all, the arbitration commission and the company often have a certain friendship, especially if you are from other places, which will give you some pressure to reduce the amount of compensation.
As long as it doesn't reflect personal reasons, you can definitely get financial compensation.