Apple claimed [0] "If you look at the last month of connections made worldwide by Apple devices, we see that IPv6 now accounts for 26% of all connections made. Twenty percent of the time, the connection could have used IPv6, but the server didn't have it enabled. And when IPv6 is in use, the median connection setup is 1.4 times faster than IPv4. This is primarily due to reduced NAT usage and improved routing." Also [1] "As of June 1, 2016, all apps submitted to the App Store must support IPv6-only networks." I guess, that is a good point for performance and revenue stream security.

Of course, IPv6 has problems in some parts of the world. IPv6-only usually means, there is IPv4 on some central gateway but your clients don't get any IPv4 assigned. There is a number of really big networks doing just that e.g. most of the mobile operators in the USA.

[0] https://developer.apple.com/videos/play/wwdc2020/10111/ [1] https://developer.apple.com/support/ipv6/