Why does pasting into proxmox shell, sometimes work, sometimes doesn't ?

Hello shodan! Are you using different consoles on the different computers? The type of console you're using influences the ability to copy/paste. See the documentation on VNC clipboard for more information. There are some threads like this one that can guide you on how to get it working correctly.
 
Hello,

In this case by console I really mean the node's shell
1738585762067.png
I searched and I could not find a console/tty/shell setting there, like there is for VMs and LXC containers
 
You should be able to see the same settings both for the node's shell and for the VM / container console, so it shouldn't matter whether it's a VM or the host itself. There's a small button on the right side of the Shell button where you could start xterm.js. You should be able to paste into the console afterwards.

Shell xterm.js.png
 
I tried both host shell and CT container shell
Same thing in both, on one computer pasting works, on the other it doesn't