Ads are still visible when you aren’t logged on, in fact they take a fare greater real estate of the screen now so Elon’s antics aside as far as advertisers go they get a better deal now.
Before the change you could scroll down past the ads for the rest of the thread, now you only see the linked tweet and then ads.
That may have worked, but Musk limited the reach of tweets by only allowing logged-in users to see the entire thread and comments.
Not to mention insulting advertisers.