In 2017 Google removed 3.2B bad ads, blocked 320k publishers, 90k websites

This merely repeats content from https://www.blog.google/topics/ads/advertising-ecosystem-wor..., thus the HN rules ask you to submit that instead.

Is there a way to review and see what has been blocked?

This kind of service should be both transparent and safe for reviewing by any interested party.

It is scary that Google has become the gate keeper.

Sorry, sounds like a drop in the bucket.