Social media profiling uses all user activity to assign interests, not just what words you search for.
It’s what you click on, watch, share, comment on, like, follow, slow down for as you scroll, what websites you visit while on a device that’s logged in to that platform, the words you use in private messages.... all of it.
When we sign up for the service, we agree to all this tracking.
There are big problems with intentional bias in targeted ads (eg certain jobs being targeted to men only, or with an upper age limit, or excluding those who live in certain postcodes)
The social media platform algorithms know an awful lot more about us all than most people realise. Not because we tell them in as many words, but because they are using incredibly powerful computational resources to crunch the data.
Political ads, foreign interference, campaigning groups, it’s on a massive scale, and really hard for the platforms to stamp out properly without preventing other advertisers from being able to spend their money on ads with that platform.
My point being, it’s complicated, and way worse than most people have any idea about, and if you think Twitter, Facebook et al don’t have you pegged into a whole lot of boxes, you’re kidding yourself.
Or maybe you’re a super geek using hyper-careful super-vigilance to remain un-tracked. In which case maybe they don’t have you pegged other than as someone to watch carefully because you’re highly likely to be up to no good with that level of caution.