Yes. My intuition tells it is last `systemd` updates.
I found this:
```
systemd System and Service Manager

CHANGES WITH 236:
        * In systemd-networkd, the IPv6 RA logic now optionally may announce
DNS server and domain information.
 — Berlin, 2017-12-14

CHANGES WITH 235:

        * INCOMPATIBILITY: systemd-logind.service and other long-running
          services now run inside an IPv4/IPv6 sandbox, prohibiting them any IP
          communication with the outside. This generally improves security of
          the system, and is in almost all cases a safe and good choice, as
          these services do not and should not provide any network-facing
functionality.

        * The IPv6 RA sender implementation may now optionally send out RDNSS
and RDNSSL records to supply DNS configuration to peers.

 — Berlin, 2017-10-06

CHANGES WITH 231:
        * systemd-resolved gained support for contacting DNS servers on
link-local IPv6 addresses.

— Berlin, 2017-07-12
```

This is main of them. RA is routr advert, in theory it should be used only when `systemd` talks to neighboring routers.