Reason for spike in number of active users

I am running a test for 4 hours, everything seems fine but I noticed a spike in the number of active users at one point. What could be the possible reasons for it.


Can you share with me, your injection profile and your test?

This is my injection profile


I am running a flow which includes 12 api.

It most likely matches a spike in response times, causing the users to live longer than usual.