> Twitter is "just a microblogging service", and yet pushed social norms around so much on certain topics that people from a decade or more ago would be surprised at the impact.

With every technological advancement or major world event, social norms move around. This is nothing new, before social media, it was the cell phone, before that it was the computer, or the war on drugs or the cold war or world war II. It's just social media's turn to take the blame for the "degradation of family values" or whatever the hot talking point is.

> It's now considered safer to say nothing online for the fear of your message being weaponised against you 10 years from now because of changes to moral values, so many people just aren't their authentic selves online any more

That's how it's always been. Nothing goes away from the internet. If you posted questionable content online under your real identity and a potential employer finds it and decides not to hire you, well, that's the price you pay for not being anonymous. Kids were often told to be careful of what they put online for at least the past 20 years. If thing X is no longer acceptable in current time frame and you said thing X years ago and it's now been brought up. You can either clarify your point if your opinions haven't changed, ignore it, express regret for making a comment on thing X and move on with your life. This is a personal accountability problem, not a societal problem. Although, I personally think that anonymity should be the default on the internet but that bridge has already been burned. Regarding people not being authentic in a large public forum, I mean, what do you expect? The entire world can see what they're posting. It's not unreasonable to show off the best parts of your life, the parts you are most proud of and to hide the struggles. Look for smaller private communities if you want real human connection.

> Another example - when I was using a voice assistant a lot, I eventually gained an instinct to call out to it as if it were second nature - and if the voice assistant is not under my control (which it wasn't), that has serious privacy repercussions, which can change my behaviour further.

You do know that you don't have to use the voice assistant right? This sounds like a you problem to be honest. It's common knowledge that these voice assistants are a privacy nightmare. Even tech illiterate people that I've met know about it but they make the trade off for convenience. It's not what I would do but its their choice.

> Another example: Ukrainian war footage on YouTube is now "inappropriate", even though it used to be widespread at first. As a result, creators stopped discussing it, or moved that content to paid platforms. As a result, the world's largest video library has a gaping hole right where this kind of content should be available for historical use.

So this is the only somewhat decent example you posted but youtube isn't a library, it's a video sharing platform. I will admit, I'm ignorant on the whole ukraine topic. But war is "inappropriate" to say the least and I can see why companies wouldn't want their advertisements to be associated with such horrific events, even if it is in a positive light. And if companies don't like it, then youtube won't push it to people's feed. I would argue it's good that they have moved to different platforms, the content is now more resilient to being taken down. And just for a quick sanity check, searching for ukraine brings up all sorts of videos. Press conferences, combat footage, people's reactions. So what exactly is being hidden?