Yeah, people are getting really upset at Google/Mozilla here but SafeBrowsing is actually a very good service. I legitimately believe that it frequently prevents malware infections and phishing on a regular basis. It is also architected with a privacy-first approach that reveals very little data to Google. And the SafeBrowsing privacy policy is actually one of Google's very tight ones.

I think Mozilla made the right choice to enable it by default. They also make it fairly easy to disable this for advanced users under the "Deceptive Content and Dangerous Software Protection" setting. (No need to crack open about:config, disabling it is fully supported.)

I understand that this may be a controversial opinion.