> As part of a planned change to update the IP address on a WAN router, a command given to the router caused it to send messages to all other routers in the WAN, which resulted in all of them recomputing their adjacency and forwarding tables. During this re-computation process, the routers were unable to correctly forward packets traversing them. "The command that caused the issue has different behaviors on different network devices, and the command had not been vetted using our full qualification process on the router on which it was executed."

From this it sounds like they might have changed the primary loopback IP, which by default is the "router-id" for various routing protocols, causing the entire network to have to reconverge. You can override the default router-id with an explicit address that does not depend on lo0 but lots of networks don't do that.

It's extremely uncommon to change the primary loopback address. It's less uncommon to add an additional one but as the article says that syntax varies by vendor: Juniper will add as additional by default, Cisco and Arista will replace the existing primary one (IPv4) unless you include the "secondary" keyword...