Or all the Container based stuff that still falls flat with ipv6 only modes. Docker still shits the bed if you dont give it ipv4 unless you do a lot of manual overrides to things. A bunch of Envoy based gateway proxies fail on internal ipv6 resources in a k8s cluster that runs on ARM64.
There is just a bunch of nonsense you have to deal with if you choose the ipv6-only route
Dont get me started on CDNs like Bunny or Load Balancers as a service like those from Hetzner, UpCloud, etc that don't work with ipv6 origins.
Source: Trying to run a ipv6 only self-hosted box on hetzner.