Mongodb cgroup: fork rejected by pids controller

CentOS 8
MongoDB shell version v3.6.17

We are seeing following error on one of our mongo replica (4 members) on a secondary member

sessionmgr12 kernel: [2754995.322942] cgroup: fork rejected by pids controller in /system.slice/sessionmgr-27717.service

We restarted the mongo process and it resolved the issue.

did you guys seen this or have more info on the same.
Do you guys think it’s bug?

Thanks
Iqbal Singh