They have been claiming that IPv6 is the future for 20 years and it still is not fully supported by even the very largest ISP.
In a lot of cases it performs much worse. Hard to say exactly why but I know a lot of times the latency to sites is much higher because the data follow a longer path. Even when it function the way it suppose to you will get less total through put purely because the length of the headers in IPv6 eat up more of the data packets.
There are only a very tiny number of sites that run only on IPv6.
The biggest issue for me is the abuse by all the large internet companies. If you use IPv6 it allows them to track all the way down to individual device because it contains the mac address and other unique...