What is the maximum penalty for breach of contract?

Some time ago, the media broke the news that "30,000 college students borrowed money to buy mobile phones and rolled into 700,000". In the incident, college student Xiao Liu signed a loan contract of "overdue default interest principal 10%". Xiao Liu later calculated that he owed 50,000 yuan and the overdue penalty was as high as 5,000 yuan per day. Judging from the incident, it is obvious that Xiao Liu suffered from usury, and the provisions of this loan treaty on overdue loans far exceeded the normal level. Therefore, netizens should not only pay attention to the way of default penalty interest, but also see whether they fall into the usury trap. In order to curb the loan risk, the bank will attach an overdue repayment clause to the loan contract. Although the regulations of each financial institution are different, generally speaking, the interest rate of liquidated damages shall not exceed the highest provisions of the current law, such as the annual interest rate of 36%.