The classic definition was basically the freedom to criticize your government without repercussions.

Conservatives now define it as the permission to spread deliberate misinformation and overt racism and bigotry without consequences from either the government OR private entities.

Because liberal used to mean "supporting liberty" (the classical definition). But it has come to mean "agreeing with a certain set of beliefs and policies", and (recently) trying to de-platform anyone who publicly disagrees. And, in our bipolar political spectrum, those who disagree with the "liberals" are the "conservatives", who are therefore the ones the "liberals" are trying to de-platform.

So the "conservatives" believe very strongly in free speech (at the moment) because it's their speech that is currently getting crimped. And, seeing the trends, they think it's likely to get worse in the future. (As, say, anything disagreeing with the current "liberal" position gets labeled "racist" or "transphobic" or something, designed to make it virtuous to censor.)

free speech is a liberal value. The conservatives, however, have tried to hide behind 'free speech' in order to compel speech from private entities, and have tried to pretend that they don't have a hammerlock on the mainstream media, and have tried to pretend that 'big tech' is nebulously conspiring against them whenever it enacts basic decency community standards.

It's not, conservatives just like to believe that they are the only ones who value it.

Liberalism is now conservative. Note that conservative and progressive as labels apply relative to the status quo - what was in your youth is not necessarily any longer.

Because liberals started censoring people.

Conservative and liberals have flip flipped on worker rights, corporate power and speech

My entire life private property was a right-wing value. Why are they against it all of a sudden?

Because Trump got banned from twitter