Thanks for this.
When Google said they were stopping 3rd party cookies, I thought it was just a simple security setting. The new system, Protected Audience, seems like 3rd party cookies without the whack-a-mole approach of listing every cookie advertisers can take, especially since there is nothing stopping data collectors from extracting data from it, like what Mozilla said in the article.
Hopefully there are fake data dumpers or cleaners for Protected Audience which would reduce the effectiveness of this system but looking how the Chrome team treats browser extensions, I doubt it.
It is creeping. If your neighbor goes outside in public and you stare at her from your window blinds, with the lights out just so you can see her ankles twice a day. Yes, she is in public and you are only looking, but the obsession is not normal behavior.