My GitLab runners being banned for no reason

I have two runners registered as project runner, deployed inside my own docker swarm cluster.

They have been working peacefully alongside with for project builds, and have been doing great on deploy tasks.

But for no reason my runners are constantly receiving Forbidden response from when checking for jobs. Our pipelines are on a total halt at this point.

I have looking at this issue, but I have no way to confirm it.

Where shall I start?