with all the halachic limitations and the conventional wisdom of statements like וְלֹא מָצָאתִי לַגּוּף טוֹב אֶלָּא שְׁתִיקָה I'm not sure why there would be any notion of freedom of speech

On the other hand, within the scope of Torah, free speech - stating your opinion - seems to be a very valid thing. I can't remember the specifics at the moment, but there is at least one famous incident of an argument over Halachah that ends with a Bas Kol siding with the outvoted Rabbi (essentially) - the speech/stated opinion is permitted - even encouraged - as long as the Halachah is followed according to the established rule (Mesorah and/or majority decision, depending on the situation).

How about אבק לשון הרע?

The Torah definitely doesn't guarantee free speech - that would require a positive statement, and there is not such statement in the Torah. A better question is if it values free speech, and if there are any sources which are relevant.

@AA Would depend on your interpretation of the halachos I think. The simplest reading is that it’s Rabbinically prohibited, but I’ve heard some apologists claiming it’s their interpretations of the verses and therefore it’s really Biblically prohibited, or the opposite approach that they’re discouraging it but it’s not strictly prohibited.

Rabbi Avi Shafran said this https://religionnews.com/2021/01/15/twitters-cancelation-of-free-speech-isnt-a-legal-question-its-a-moral-one/