I've developed a few browser extensions, and every week I receive numerous emails with "revenue offer". Some experienced developers know that offers like these will inject malware into the browsers of your users, but scammers who make these offers will not tell you about it. They offer "integrations" that don't look so suspicious. Imagine how many developers have accepted these offers. Then look at the number of extensions in your browser and think about how much risk there is that you have an extension with malware.
From what I’ve experienced with my extension, every update has to go through a review process. Firefox is pretty fast, chrome takes a few days and edge takes a while (opera hasn’t finished reviewing my first version, so I stopped trying with them).
The only time I failed a review was early on when my build script choked and I submitted an empty file to Chrome (whoops). So I can’t really tell how good those reviews are, but I’m not planning on testing them. I just know that they exist