High idle CPU usage (ds-lite ?)

To me that looks like a DDoS via neighbor solicitation & RA.

Sounds like your ISP has set all IPv6 peers to see each other.
Additionally, the ISP nexthop spams you with RA every second

I would contact the ISP with that data, and ask if that is intentional.

I haven't checked my own WAN with wireshark or something, but your screenshot looks crazy to me at the first glance :frowning: