If freedom of speech is absolute, how come it's not applied for private spaces and for the Internet?

No freedom is absolute.

Perjury

False advertising

What thing happened to you as a child that you haven’t let go of to this day?

Insurrection

Trade secrets

If you’re wondering why free speech doesn’t apply to the internet, it’s because you have no right to use other people’s stuff for free.

David Hogg to depart as DNC vice chair after months of turmoil - The Washington Post

You have freedom to travel. If I loan you my car, I can tell you not to take it out of town, because it’s mine, you have no right to use it, and if I give you permission to use it I can tell you what you can and can’t do with it.

That’s what it is. You have no right to use other people’s stuff. If people let you use their stuff, they can tell you how you can use it, and they can tell you to stop using it any time they want.

Terroristic threats

Exclusive | Ken Moelis to Step Down as CEO of His Investment Bank - WSJ

You have freedom of speech. If I loan you my computer, I can tell you not to use it for certain things, because it’s mine, you have no right to use it, and if I give you permission to use it I can tell you what you can and can’t do with it.

Conspiracy

Revenge porn

Can a teenager take boron? (Read my comment below for more context if you wish)

Fraud

Freedom of speech does not apply to:

Threats of violence

Fiserv’s stock surges as it teams with Circle to join the stablecoin party - MarketWatch

HIPAA violations

Insider trading

Child pornography

Non est eum facere impedit aut dignissimos tempora.

Revealing classified information

And much, much more.