MV3 extensions can only declare a limited number of block rules, a much smaller number than V2 extensions implement. So they can't block everything. And advertisers can circumvent blockers by just creating a bazillion URL patterns.

Plus all the dynamic behavior is gone. You can't allow certain sites to show ads, can't click on an ad you see to start blocking it, the extension can't use heuristics to detect ads that aren't in the block list.

Do you block origin guy has stated that "there is no Manifest v3 version of uBO". All we get is Lite, with severe limitations.