Why I am Getting Unreachable Error While Using Higher Forks and Bastion Host in Ansible?

Issue

I am intermittently getting Unreachable error while using higher forks value, while using bastion host in the middle to connect to the remote node.

If I use forks = 10, it works fine, but if I increase forks to 20 or 30, it randomly gives an Unreachable error on random remote nodes.

If I don't use bastion host and directly try to connect to the remote nodes with higher forks it works fine.