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.