Why isn't the FBI raiding all Silicon Valley companies like Facebook, Twitter, Instagram, WhatsApp, TikTok, Reddit, Google, Yahoo, YouTube, Disqus, Wikipedia for censoring the World through their Ban cartel violating the constitution freespeech laws?

Companies that are privately owned, owned by stockholders, etc. are also covered by this. These companies cannot be forced to provide space or a platform for speech they do not agree with. This is freedom of speech. I realize you may disagree.

Should newspapers be forced to print every letter ...

Government owned companies are also covered by this, but these companies must allow speech the company may not agree with.

Using ChatGPT to write essays may be eroding critical thinking skills - Phys.org

They have not violated the U.S. Constitution and freedom of speech laws. Dunno about other countries.

Restrictions of course apply. See Supreme Court rulings on what can be restricted, i.e. child porn, inciting to violence and a couple of others.

What arguments like this fail to recognize is 1A means you have the right to keep your damfool mouth shut. 1A means you cannot be forced to say anything, a right backed up by 5A. 1A and 5A as they apply to speech prevent government from forcing you to say something AND stop government from not letting you speak.

Can you fly an American flag in the UK in your own private property there? What is the UK’s government stance on that? And if yes, do you also have to fly the UK flag or the American flag can fly solo?

Lemme make this simple - Freedom of the press belongs to the person who owns the press. You don’t like what a particular press (the social media you reference above is the press in this case) does, start your own and you make the rules.