Chrome's Manifest V3 Push Signals Changing of the Guard
The updated version is hostile to extension developers and users, and this shared adversity may prove to be a powerful catalyst.

Following the initial manifest V3 announcement in 2018, browser extension developers did not take long to figure out that manifest V3 makes browser extensions less useful, less powerful, and harder to build.
Chrome is well-positioned to steer browser extensions toward its vision for manifest V3. Chromium browsers (Chrome, Edge, Opera) make up over 80% of worldwide desktop internet traffic, and with 180,000 extensions the Chrome Web Store is by far the largest extension marketplace.
Manifest V3's chaotic rollout left the extension developer community with a bad taste in its mouth. Advertising-averse users will be quick to notice the diminshed efficacy of ad blockers. With Mozilla's recent announcement that it will continue to support the blocking WebRequest API, aggrieved developers and users now have an obvious refuge.
Meanwhile, the mobile extension landscape is shifting. In 2020, Apple added support for browser extensions in iOS Safari. Though developers may balk at publishing browser extensions in the App Store, Apple is advancing browser extensions by bringing them to the most popular mobile browser. Chrome for Android does not support browser extensions, and there is no indication it ever will.
Chrome remains the hegemon of the browser world, so it is difficult to imagine it being unseated. Internet Explorer once enjoyed a similar dominant market share, but the speed of the exodus was shockingly quick.

Building Browser Extensions by Matt Frisbie
The complete reference for building modern browser extensions in Chrome, Firefox, Edge, and Safari.