Recently¹ tried to bring up a "Flexible" Postgres server (Azure's managed PG offering) on an IPv4 (four) only subnet. The request hung, for two hours, before finally failing with a generic "internal error". Retried, same result. Contact support. Flexible PG doesn't support being brought up on a vnet with IPv6, even if it is on an IPv4-only subnet, even if you have no intention of connecting to it over v6. Want that service? No IPv6 for you, I guess.
¹okay, apparently April, and even just the request to get the limitation added to their documentation of the limitations of IPv6 is still pending…
Don't look at Azure then, it's not interesting at all. It's just sad.
They NAT IPv6, and hand addresses out in blocks of 16.
No, not /16 address blocks. Sixteen at a time. Six and ten.
I wish I was kidding.