Follow up from T375464#10170262
Only the LVS in eqiad/esams/drmrs still have their BGP config manually done on the router side. See https://netbox.wikimedia.org/dcim/devices/?cf_bgp=False&name__isw=lvs&status=active&sort=name
"fixing" this should be relatively straightforward, along the lines of, for each site:
1/ flip the BGP flag to true on all the site's LVS
2/ run Homer on the LVS' neighbor (either the core router or the ToR switch, depending on the type of vlan it's in)
The change should be close to a NOOP as it would replace and existing configuration by a similar one. Depending on the diff, the BGP sessions might not even bounce.
To be done under the supervision of Traffic and Netops.