LnL: 
`fe80::/64`means: "if packet matches any `fe80:*:*` in 64 bits - send it to ...".

Basically that is enforced route for any `fe80:*:*`.
Routes with higher priority can be:
* `fe80::/64` with lower metric.
* If packets would have configured subzone, and route `fe80::/65-128`.