Mozilla has decided to split from Google and continue to support existing ad blockers in the upcoming extension changes being proposed by Google as part of the Extensions Manifest v3. This includes ad blockers such as uBlock Origin, which is a highly popular extension for filtering web content, used by over 10 million users. Google says that ad blockers developers should use the declarativeNetRequest API instead, which allows extension developers to create filters and rules that cause the browser, not the extension, to strip content or resources from a visited web page.
Source: https://www.bleepingcomputer.com/news/software/mozilla-will-support-existing-ad-blockers-in-extensions-manifest-v3/