The legal concept of "free speech" originally meant "speak truth to power".

Highlight on truth and power.

Now it's being co-opted to allow for propaganda, disinformation and even far-right apologists.

And far left apologists too!

(this is a pretty clear example of exactly why we need free speech)

No. Not even a little. You cannot highlight your baseless premise and make it more true.

Free speech means and has always meant "to say whatever you want and for whatever reason."