IPv6 was drafted in 1998, and ratified in 2017. 7 years after becoming "official" only 50% adoption rate world-wide is not what I would call stellar either.
It's kind of a misunderstanding to say that IPv6 became official in 2017.
The IETF has multiple standardization levels, with Proposed Standard being the first and Internet Standard being the last (there used to be Draft Standard in between but it was eliminated). Proposed Standards are deemed ready for deployment and lots of important protocols (e.g., TLS, QUIC, etc.) are at Proposed Standard. IPv6 went to PS in 1998, and people have been trying to deploy it ever since, so it's really more like 25+ years since it was official.
Honestly... 50% in 7 years is an impressive achievement, and far from being awful. People often compare IPv6 adoption to things such as HTTPS adoption, but upgrading to IPv6 requires hardware changes on both the ISP side and the customer side, and as we all know, hardware upgrades take forever. It's not unusual to see >10yo equipment running in the wild.
Also even for HTTPS adoption - it was introduced in 1994, and in 2010 even major websites like google and facebook were basically only bothering to secure their login page which is how Firesheep came to be. It was only really that illustration of the business need that caused anyone to start bothering, and despite that demonstration, adoption was below 50% as late as 2018
Industry doesn't adopt a thing until there is a need for it. In 1998, there really wasn't a need for it. Now there is. So now it gets adopted. News at 11.
Also, it's worth to keep in mind the delay on the hardware replacement. There were home routers which didn't support ipv6 even 7 years ago. And there many home routers deployed today which are over 7 years old.
Also, my provider fully supports IPv6 and so does my hardware, but I have to click a button in the control panel to activate it explicitly. That's practically around a million of people who could be on IPv6 right now if they just opted in.
I’ve noticed that the Ubiquiti UDM Pro router has IPv6 turned off by default; and I don’t really want to change the defaults, because idk, maybe something will subtly break, and in any case it works fine as-is…
It looks like it's going to be a few years until not enabling it will start subtly breaking things. ;) It's a trivial change to reverse, so if you're interested, give it a go.
IPv6 was drafted in 1998, and ratified in 2017. 7 years after becoming "official" only 50% adoption rate world-wide is not what I would call stellar either.
Also, looking at that chart it's closer to 40%...