I think there's more involved than simply undoing a change. Apart from the obvious tedium of chasing upstream code changes, the extensions themselves have to be installed from a willing (and trusted) repository. The chrome web store can omit extensions that use an API in an unsupported way.

Brave already integrates ad-blocking at a lower level than the webRequest API, so this is less of an issue, but you sacrifice your choice in blocker.

https://brave.com/improved-ad-blocker-performance/

The recent Chromium’s Manifest v3 controversy around the overheads of the various extensions using the WebRequest API to inspect and potentially block undesired requests did not affect Brave as requests are processed natively, deep within the browser’s network stack.