Requests for haproxy to the server part are not closed

Good afternoon friends!
Recently, on the Haproxy load balancer, it has become permanently stored a large number of requests equal to the number of real user requests at the time of load increased by *2. earlier there were about 1000 user sessions during working hours, and 100 at the time of inactivity. Now, relatively speaking, 2000 and 1000 at the time of inactivity. There is a suspicion that sessions are not closed, while there is no load on the frontend server. All sessions hang on haproxy. Can you tell me what caused and how to solve the problem?