>Tim Berners-Lee tries to make the internet a place where you can choose, what it "forgets". At least that were the news I got from the 2010s and early 2020s.

Tim Berners-Lee created the web, not the internet, which is what chat apps use. Also, unless you can provide some direct quotes about it being designed for "forgetting" stuff, I have no idea where these "news" you got came from.

>As for how: DRM-like tech in the hands of users should allow for that.

If it's in the hands of the users, i.e. open source, it can be disabled at any moment, which is exactly what my reply already addressed.