See here: https://bugs.chromium.org/p/chromium/issues/detail?id=113549...
> We have always intended to provide support for this functionality in Manifest V3 (for both user-installed and force-installed extensions), and have been iterating on different possible approaches. Our tentative plan (which is not yet finalized) is that the Manifest V3 version of this capability will require extensions to request a new permission scoped to intercepting authentication requests, but will otherwise allow extensions to handle these requests in a similar manner to how they do in Manifest V2.
> The permission string and end user facing warning string have not been finalized yet. Also, we have not yet finalized how this new permission will interact with other permission grants, but extensions that currently have the webRequest permission and broad host permissions will likely not require an additional grant for this permission.