Broken arrow keys for browser access to proxmox and ESXi

Just throwing this out there in case anyone else is seeing something
similar or has any ideas.

I'm using NetBSD to access some proxmox and ESXi systems via a web browser.

In each case when I try to use the in-browser console access to any of
the VMs the arrow keys are broken - specifically down arrow appears to
return newline, and left & right arrow nothing.

This has been confirmed in Firefox and Chromium.

proxmox is using the https://novnc.com/info.html to provide the
console, "Who Can Tell" regarding ESXi, but as we're retiring our last
ESXi box soon I'm less concerned, other than it is interesting it has
the same behaviour.

From a hunt around I see reports of similar behaviour with
- xorgxrdp from 2016 - https://github.com/neutrinolabs/xrdp/issues/355
- XRDP/x2go - https://forum.proxmox.com/threads/novnc-arrow-keys-misinterpreted-when-connected-via-xrdp-x2go.164816/
- freebsd install issue
https://forum.proxmox.com/threads/problems-with-keyboard-in-freebsd-installation-as-vm.55307/

I'm wondering if novnc might be hardcoding a set whatever Linux uses
as standard keysyms for its keys...

Thanks

David