For those of you having this problem recently, I believe its to do with an update that's happened recently.
My trouble shooting steps would be, as before mentioned, making sure your pool is connected in the TrueNAS ui.
After that, Go to network - Global config, settings.
And make sure that the DNS Servers are listed as
Nameserver 1 - 1.1.1.1
Nameserver 2 - 8.8.8.8
after changing that make sure to SAVE and then reboot your server.
TrueNAS SCALE’s apps subsystem might have been using a non-functional local DNS server (Typically your IP), causing container pulls to fail. Overriding the DNS to use public resolvers (1.1.1.1, 8.8.8.8) fixes the issue by ensuring reliable domain resolution inside Kubernetes
