Mongodb User Information Lost

  mongodb, question

I have just used mongodb. During the use, I suddenly found that the wrong authentication failed yesterday. Upon checking, I found that the previously created users in mongodb were gone. Looking through mongodb’s log, we found the following:

2017-11-26T00:19:15.531+0800 I ACCESS   [conn4043] Removed deleted user airspace@airdata from session cache of user information.
 2017-11-26T00:19:20.679+0800 I ACCESS   [conn4056] Removed deleted user airspace@airdata from session cache of user information.
 2017-11-26T12:59:21.460+0800 I ACCESS   [conn4062] Removed deleted user airspace@airdata from session cache of user information.
 2017-11-26T13:03:45.733+0800 I ACCESS   [conn4057] Removed deleted user airspace@airdata from session cache of user information.

Is this mongodb’s own mechanism or has it been hacked?

Have you found the reason? I have also encountered this problem. It is a headache. What is the cause of this problem?