It puts a UK user in a weird situation. On one hand, the more countries that join in (and I've heard of US states too), the more likely it is that age verification becomes well supported and I continue having access to the wider world's internet. On the other hand, we've reached a very thick part of the wedge already: this is terrible for competition and I do not trust any state with this power.

The best path is one of calamitous implementation that scares off other countries and embarrasses this one into a u-turn. But it's increasingly unlikely.

Do keep in mind that the EUs approach is very different from the UK one.

The UK law is basically a "go figure it out", which inevitably leads to making shady deals with third parties that are now handling the data of citizens... privacy and data leakage issues abound.

The EU meanwhile is working on a whitelabel application that can confirm nothing other than "this user is above 18" (which they can do because the EU has national ID for basically anyone living in it. It also works for another set of age ranges, as the idea is to also use this to confirm stuff like buying alcohol) and is designed to be easy to implement for anyone without having to get approval from the EU first. (Technical specification is available here[0]). It's not perfect (last I saw, they're apparently tying it to Google Play Services for device verification), but it's a far better attempt than the UK/Australia are doing.

[0]: https://ageverification.dev