IPv6 looks so Rube-Goldbergy to my eyes that if I squint just a little tiny bit and put a very thin thinfoil hat on, I could nearly swear this complexity is there by design. For example so backdoors allowing exfil through ICMP are impossible to detect.
IPv6 is chatty. So chatty.
There are networks where a single unaccounted for packet means something abnormal is going on (and at the very least requires enquiry): how does that work with IPv6?
An issue with these big design-by-committee thinggies is that often one or two in the committees are little rats working for the man.