Why was my ec2-instance terminated by elastic-beanstalk?

I have an EC2-instance inside Elastic Beanstalk environment, which was terminated for reasons unknown. The only information I possess is state transition reason

Client.UserInitiatedShutdown: User initiated shutdown. 

I use this environment alone and I am sure that I haven't initiated shutdown by myself, so this must be EB.

In events there is only one record: instance 'i-6252b1a3' has been removed from your environment. There is no mention of terminating this instance in EB logs too. How can I else get information why this instance was terminated?