Firefox's are, nominally, reviewed. I don't know if Chrome's are, but I would've assumed that they are- even if by some automated tool(s).
Granted, I'm sure malware slips through. But, what security danger is there to a user if an extension blocks a network request? Manifest V3 eliminating the ability to block network requests is NOT for user security. The absolute best excuse they can come up with is that it has something to do with performance, but that's also bullshit because I'm 99% sure I can find plenty of ways to make a Manifest V3 extension waste CPU and/or memory.
Granted, I'm sure malware slips through. But, what security danger is there to a user if an extension blocks a network request? Manifest V3 eliminating the ability to block network requests is NOT for user security. The absolute best excuse they can come up with is that it has something to do with performance, but that's also bullshit because I'm 99% sure I can find plenty of ways to make a Manifest V3 extension waste CPU and/or memory.