Comment # 8 on bug 966999 from Lorenzo Desole

To cut a long story short: I am not convinced it's a bug in NetworkManager.

Network manager has supported privacy extensions for about 2 years now.

After some digging I found this:
https://bugzilla.gnome.org/show_bug.cgi?id=705170#c5

The point is, in my case:

) NM fails to give network interface any temporary address
2) NM gives network interface an IPv6 address as /128 and not /64
3) NM prints a warning in logs that says "libnl does not support extended
IFA_FLAGS ..."

Basically it behaves exactly as described in the post I quoted.

I'd start looking into libnl.