I would have liked to know more about what the process of analysis looks like. Considering the scale of the Web, it would have to be automated, but all the documentation talks about "(re-)reviewing" and "examining" that seems to suggest some sort of human intervention, and if automated I don't quite understand why it's taking so long to review sites; all of mine still have a status of "Not reviewed".

Some more info here:
About Chrome ad filtering [support.google.com]
About ad experience reviews [support.google.com]
Testing Chrome ad filtering [chromium.org]

First, let's be quite clear that this is largely a PR exercise taking aim at a minimum possible most egregious cohort; G is on record (re- WSJ):

Mr. [Scott] Spencer [Director, Product Management, Sustainable Advertising, Google] said Google has given ample warning to the affected publishers. He said that less than 1% of the web's most visited sites—under 1,000 of them—are currently out of compliance with the rules.

That said, it is useful to know just what G et al are actually targeting (re- Coalition for Better Ads [betterads.org]):
Note: apparent current thresholds noted, thresholds can, of course be modified at any time.
Desktop Web Experiences
* pop-up ads; MAY be restricted to interstitial ads.
* auto-playing video ads with sound; MAY only apply to inline video with sound.
Note: NOT yet tested are video ads that appear before (“pre-roll”) or during (“mid-roll”) video content that is relevant to the content of the page itself.
* prestitial ads with countdown; NOT egregious if also able to be dismissed immediately.
* large sticky ads; NOT egregious if cover less than 30% of screen. MAY be restricted to screen bottom sticky ads.

Mobile Web Experiences
* pop-up ads; MAY be restricted to interstitial ads.
* prestitial ads; MAY be restricted to blocking content.
* ad density greater than 30%; actual threshold is ad being greater than 30% of vertical height of main content portion of page.
* flashing animated ads; MAY be restricted to rapidly changing background and colours.
* auto-playing video ads with sound; MAY only apply to inline video with sound.
Note: NOT yet tested are video ads that appear before (“pre-roll”) or during (“mid-roll”) video content that is relevant to the content of the page itself.
* postitial ads with countdown; NOT egregious if also able to be dismissed immediately.
* full-screen rollover ads; ONLY applies if (1) cover greater than 30% of screen and (2) float on top of page content. NOT egregious if scroll inline with content.
* large sticky ads; NOT egregious if cover less than 30% of screen. MAY be restricted to screen bottom sticky ads.

All the above are easily calculated inputs and a 'bare minimal' acceptable standard that can be adapted depending on public opinion aka whether it has an affect on actual real ad blocker use. Sort of the disruptive ad version of the 1-second 50% viewable for ad impressions solution after that (advertiser rather than user) backlash of paying for ads that no one ever saw.

Anyone seeing the report populated in GSC yet?

My properties still show "Not Reviewed" although I now have Regions defined for both Desktop and Mobile.

Also, as I reported here [webmasterworld.com] the new Chrome Ad Blocker asks if you want to block certain ads. I haven't seen this on enough pages to get a sense of what ads fall prey to this action, but I've seen it on a couple different sites as well as YouTube videos.

I am soo surprised, no one after 2010 is replying to such an important topic. ?
Google is loosing consideration ? I dont think so,
Does google hires and fires its clientele (even after ages of service).