Can't provision jenkins slave pods due to "Unknown client name" error
Self reply:
I was able to provision slave pods again after I upgraded my Jenkins and Kubernetes plugin to the latest.
The version I'm at is Jenkins 2.289.1, and Kubernetes plugin 1.30.0.
I had a similar issue once. I can't recall the exact details but it either had to do with an update to the jcasc plugin or Jenkins itself. To fix it I updated the args specified for the agent to be "^${computer.jnlpmac} ^${computer.name}". From what I recall this was to avoid some premature interpolation.