Awesome! One of the few things more rewarding than solving someone's issue for them is to see them figure it out on their own.
I don't have the exact answer for your SSL certificate verification issue. I can tell you that it's related to an expired certificate, but finding this may be a bit tricky. I don't use Kube on TrueNAS so I've not got much reason to dig into it (sorry). A potentially somewhat similar expired cert issue came up about a year ago and is discussed at
Posted in response to a staff request, this is intended to help answer the "certificate is expired" issues. SSL underpins most network session security on the Internet. Historically, this was implemented with self-signed certificates (a bad idea), or through commercial certificate authorities...
www.truenas.com
but no promises of anything other than some help understanding how this all works.