Firefox's implementation of MV3 allows both async permission-less blocking (declarativeNetRequest API) and permissioned synchronous blocking (webRequest API). u

Firefox's implementation of MV3 allows both async permission-less blocking (declarativeNetRequest API) and permissioned synchronous blocking (webRequest API). uBO Lite uses the former to provide an ad-blocker without read/write permissions. You can still write a unsandboxed extension with MV3 (and in Firefox it will still be able to intercept requests, while in Chrome it will not be on the network hot path) but the point is that you can also write a permission-less ad-blocker now, which is what I want.