> Its a real pity they are the worst privacy-vioolating tools ever.

What do you mean?

They read your entire page content, they have access to all your information.

But there are free software ad blockers like uBlock Origin.

if uBlock got compromised as an extension even for 1 day, the amount and value of data uBlock can collect will make anyone very very rich.

It's on the level of saving passwords as texts in terms of privacy.

How is it different from any other browser extension? They are all like that, aren't they?

It depends on the permissions: uBlock has permissions to read the entire page on any domain. Some extensions only limit themselves to specific domains, or don't touch that at all.

uBlock still reads your bank website, etc.