The issue here is that in order to do its thing, uBlock Origin requires quite extensive access to the browser context, including the ability to intercept network traffic.

It’s pretty easy to see how this could be abused by malicious extensions, and security is the stated reason behind many of the Manifest v3 changes.

So it’s not clear that this is Google “being evil”, so much as it is trying to force web security forward, at the expense of user experience.