Firefox is supporting Manifest v3 extensions however they are not imposing every limitation Chrome is on them and they are continuing to support features outside the scope of v3 like blocking webrequest.

A lot of the changes in v3 are actually pretty sensible, it's just 10% of the stuff shoehorned in creating 90% of the friction.

https://blog.mozilla.org/addons/2021/05/27/manifest-v3-updat...

Web Extensions have never had a spec before. So of course Google is taking the initiative to aggressively re-define & cut down what an extension is, at the exact moment they try to turn it into a cross-browser standard.

Firefox will make it possible to upload manifest V3 extensions to their store (eventually). It's a good thing because it makes it easier to make an extension that works unmodified for both.

Chrome is additionally planning to remove support for manifest V2 as well, Firefox can't start to do this because they don't support V3 in their store yet.

Safari had the same concept first.

FF is funded by Google. They have no choice.