Originally Posted by plunet

Whilst it might be assumed that this is some config change that cloudflare or IB have made to block NordVPN, but it could well be an IP address block on a wider range of IP addresses that has been involved in some inappropriate activity that has inadvertently included the NordVPN address range. Or something else entirely different.

As someone who has experience of IT Operations, and in support of IB techies, I cannot imagine they go around making random config changes and making configuration more complex than needed.
Having posted the rayIDs hopefully IB tech support can get to the bottom of this.