It's going to be so easy to determine who you voted for, given a record of every TV show and news programme you've watched, to 90% accuracy. Or to determine if you'd be a "corporate culture fit" when you're next looking for a job. Or an apartment. Or to find whether anything matching the hash of some trade secret documents was displayed on your TV (or ever connected to it [1]) - the "advertising" firm will be forced to hand over documents on you through lawsuit discovery and the wonderful 3rd party doctrine.
Have you been watching media associated with "woke subversion"? "Islamic extremism"? "Far-right hate"? "Incitement to subversion of state power" [2]?
They're not building an advertising profile. They're building a profile. Ads are just the most common known use-case at the moment. But the profile will remain long after ads become the least of your concerns. Consider how such a profile would have been used during the cultural revolution.
If the government required you to submit a record of every book you read or own, people would rightly freak out. How is this any different?
[1] LG Smart TVs log USB filenames and viewing info to LG servers - https://news.ycombinator.com/item?id=6759426
[2] Hong Kong's Tiananmen activists sentenced to up to seven years in prison - https://www.bbc.com/news/articles/cvgyvk2djk4o