### What happened?
I immediately disconnected the client after connecting to EM…QX. Set the Keep-Alive Multiplier to 1 and the client keep-alive time is 120. The EMQX actually disconnected after 240 seconds.
**I set the Keep-Alive Multiplier to 1 only because if it is set to 1.5, the actual timeout is 360 seconds.**
### What did you expect to happen?
The EMQX disconnected after 120 seconds.
### How can we reproduce it (as minimally and precisely as possible)?
_No response_
### Anything else we need to know?
I directly turned off the power of the embedded device to disconnect MQTT, so this may not be reproducible on the PC.
### EMQX version
v5.2.1
### OS version
_No response_
### Log files
2023-09-26T10:25:09.971438+08:00 [MQTT] da16x_B4BE@192.168.1.161:38554 msg: mqtt_packet_received, packet: CONNECT(Q0, R0, D0, ClientId=da16x_B4BE, ProtoName=MQIsdp, ProtoVsn=3, CleanStart=true, KeepAlive=120, Username=devices, Password=******, Will(Q2, R0, Topic=smc_will_dev Payload={"sn":"008DB260"}))
2023-09-26T10:25:09.972369+08:00 [SOCKET] da16x_B4BE@192.168.1.161:31105 msg: emqx_connection_terminated, reason: {shutdown,discarded}
2023-09-26T10:25:09.973186+08:00 [MQTT] da16x_B4BE@192.168.1.161:38554 msg: mqtt_packet_sent, packet: CONNACK(Q0, R0, D0, AckFlags=0, ReasonCode=0)
2023-09-26T10:25:09.977985+08:00 [MQTT] da16x_B4BE@192.168.1.161:38554 msg: mqtt_packet_received, packet: SUBSCRIBE(Q1, R0, D0, PacketId=1 TopicFilters=[smc_response_D0B065A8(#{nl => 0,qos => 2,rap => 0,rh => 0})])
2023-09-26T10:25:09.978404+08:00 [SUBSCRIBE] da16x_B4BE@192.168.1.161:38554 msg: subscribe, sub_id: da16x_B4BE, sub_opts: [nl: 0, qos: 2, rap: 0, rh: 0, sub_props: []], topic: smc_response_D0B065A8
2023-09-26T10:25:09.978866+08:00 [MQTT] da16x_B4BE@192.168.1.161:38554 msg: mqtt_packet_sent, packet: SUBACK(Q0, R0, D0, PacketId=1, ReasonCodes=[2])
2023-09-26T10:29:09.974537+08:00 [SOCKET] da16x_B4BE@192.168.1.161:38554 msg: socket_force_closed, reason: keepalive_timeout
2023-09-26T10:29:09.975092+08:00 [PUBLISH] da16x_B4BE@192.168.1.161:38554 msg: publish_to, topic: smc_will_dev, payload: {"sn":"008DB260"}
2023-09-26T10:29:09.975407+08:00 [SOCKET] da16x_B4BE@192.168.1.161:38554 msg: emqx_connection_terminated, reason: {shutdown,keepalive_timeout}
