[spinax]

I'm literally on Arch using NetworKManager, when creating a new connection it defaults to Stable Privacy in the dropdown, but EUI64 is listed first in the dropdown itself. So, since you didn't actually state which one to use, now what? Point being: don't be condescending claiming "outdated OS", IPv6 is a minefield of footguns and there are many of them just like this choice.

[neilalexander]

The sane default is Stable Privacy. It's a good thing that NetworkManager agrees if it has offered that to you as the default. Ultimately though any confusion that arises from how that option is presented to the user is really a bug in NetworkManager and not in IPv6. The footgun here is that NetworkManager allows you to change it so easily without offering any explanation as to what changing it will do.