Mozilla’s approach to Manifest V3: What’s different and why it matters for extension users
Mozilla’s approach to Manifest V3: What’s different and why it matters for extension users

blog.mozilla.org
Mozilla’s approach to Manifest V3: What’s different and why it matters for extension users | The Mozilla Blog

Extensions are like apps for your browser, letting you customize and enhance your online experience.
TLDR: They are keeping manifest v2 as well so devs have more options, and specifically keeping the API feature that ublock origin uses.
Pretty much already known stuff to those who follow these kinds of thin gs