Free speech means that the gov can not put you in jail because of that but private people can punish you for spreading fake news. This is there freedom.
Yes you can cry then that this is cancel culture but every time someone cries about cancel culture usually its because the person said something stupid which people did not like and now want's to take away there freedom of speech.
But 'cancel culture' wouldn't be an issue if that was all - if individual people simply chose to stop associating with the wrong-thinker. Not even if a lot of people did at once.
The problem is that when those people are not individual fellow citizens, but the "Trust & Safety Team" or the "Anti-Evil Team" at $Megacorporation, they don't just stop doing business with you - they can effectively cut you off from most of the rest of the world, whether or not the rest of the world wants it.
Simply put, the problem is that they have too much power. They have the same freedom of association as private citizens, but their ability to punish people is incomparably greater and isn't subject to the same restraint as the government's.
If Facebook/Google/Amazon/Cloudflare deny your their services you can still always find a new provider (see Gab). If the government shuts you down, you need to emigrate to start back up.
Sure, its a PIA to re-setup a service meant for AWS not on AWS but that's really the core of AWS's offering. Big Tech is not the grocery store, you will live without twitter, you will not live without food.
The power a corperation has is governed by the Charter that was (now implicitly) granted by the State they're incorperated in. If you think they have too much power in their Charter complain to that state.
Quite. I loudly support breaking up the megacorps and try to avoid depending on them, for what little I can do as a European citizen.