Google is definitely NOT penalizing PBNs in general, there is just no way to ethically do such a thing. They would never just scan GoDaddy auctions or sites hosted on a shared server and deindex everything, it's just not possible. With that said, many people fail to do at least one or more very important steps in setting up a PBN. The following mistakes are often made:
1) All sites are hosted on the same shared server with the same IP.
2) Sites use spammy spun content. Contrary to popular opinion, Spun content is still okay, as long as it's 60-70% unique and is not the ONLY content on your website. On my micro niche sites I auto-blog one post a day and drip the first 10-20 articles in which are all real, 100% original, written by me personally. If you are ever penalized for crap content, it wont slam your whole PBN either, it will only impact the website with crap content.
3) Too many links with unnatural anchors. Again this would only hurt one site, not the whole network.
4) Keyword stuffing, etc... Once again, it will only impact the site that's being stuffed, not the entire network.
With that said, if you are making the same mistakes on all your sites, it's only a matter of time before they run into issues. Just be smart about it and you'll never have any issues. I have just over 50 sites in my PBN. All of my domains I found through FreshDrop, pr2-. I have a few different hosting accounts and I don't have more than 3-4 sites on an IP. If you have 100 sites, you don't need 100 IPs, 25 will do just fine. Just remember to maintain content quality and anchor naturalization, you aren't going to have any problems.