Wireguard interfaces have IPv6 addresses that are auto-generated and cannot be disabled; note the two times I tried to tab complete:
trae@cr01a-vyos# set interfaces wireguard wg2 ipv6
Possible completions:
> ospfv3 IPv6 Open Shortest Path First (OSPFv3)
> ripng Routing Information Protocol (RIPng)
[edit]
trae@cr01a-vyos# set interfaces wireguard wg2 ipv6 add
Configuration path: interfaces wireguard wg2 ipv6 [add] is not valid