Yet another over-subscribed device to rewrite packets between you and your destination. Spontaneous connection failures due to port exhaustion or overly aggressive connection timers/recycling. Lack of public to private connectability due to absence of port mapping, or any way to influence the configuration of your carrier’s device.
> How many humans browse internet with IPv6 only devices?
If you browse the net on your phone, it's likely you already do or sit behind some kludged up NAT situation which - among other things - severly curtails your freedom to interact with other devices on the internet.
And things aren't going to improve in that regard given the shortage of V4 addies.