I don't think moving off IPv4 is on anyone's radar yet, unless you're buying VPS services that often come with a discount when you run on IPv6 only. In practice, you'll probably always have IPv4 connectivity of some sort, even though it's probably going to become more and more likely that that connectivity is attained through CGNAT.
Github is especially infuriating. For a few weeks, they ran a test, everything seemed to work great, and then they reverted to IPv4-only again.
Email servers live a decade or two in the past anyway. Disabling SSL 3.0 or TLS 1.0 support on email servers is still something you can't do without risking email deliverability problems. Microsoft Outlook's support and spam filters don't even seem to be aware of IPv6 capable mail servers (despite their headers showing they've been using IPv6 internally for ages).
I do wish IPv6 would be leveraged more, but the fear that maybe things work slightly less well for a minority of customers seems to be freezing every attempt at actually making use of the tech.
The reason you may be seeing weird IP behaviour from mobile carriers probably has to do with the way IP on mobile networks works, though. If you're on a call driving down a highway or sitting in a high-speed train, your phone will be doing handovers over and over again, and your IP address needs some form of stability. You may even cross a border and switch to a foreign network and the entire stack is supposed to maintain a seamless connection. There are special routing systems set up within cellular networks (some of which make excellent use of IPv6 features) that will make it very difficult to provide "normal" static GUAs to cell phones. Things are made as normal as possible, but it's not as easy to accomplish that kind of stability as you would with a fixed-line home internet connection.
Github is especially infuriating. For a few weeks, they ran a test, everything seemed to work great, and then they reverted to IPv4-only again.
Email servers live a decade or two in the past anyway. Disabling SSL 3.0 or TLS 1.0 support on email servers is still something you can't do without risking email deliverability problems. Microsoft Outlook's support and spam filters don't even seem to be aware of IPv6 capable mail servers (despite their headers showing they've been using IPv6 internally for ages).
I do wish IPv6 would be leveraged more, but the fear that maybe things work slightly less well for a minority of customers seems to be freezing every attempt at actually making use of the tech.
The reason you may be seeing weird IP behaviour from mobile carriers probably has to do with the way IP on mobile networks works, though. If you're on a call driving down a highway or sitting in a high-speed train, your phone will be doing handovers over and over again, and your IP address needs some form of stability. You may even cross a border and switch to a foreign network and the entire stack is supposed to maintain a seamless connection. There are special routing systems set up within cellular networks (some of which make excellent use of IPv6 features) that will make it very difficult to provide "normal" static GUAs to cell phones. Things are made as normal as possible, but it's not as easy to accomplish that kind of stability as you would with a fixed-line home internet connection.