Yes, they are!
In fact, a lot of the well-built ones are producing better results than ever.
What you really should be asking is whether high-quality PBN sites still work; the answer would be a resounding ‘yes!’
On the flip side, if you're asking about sloppy, badly put-together, low-quality domains containing PBN networks, then chances are they're not doing all that well.
Google is getting smarter.
We all know that in the blackhat game, we are running in an arms race with a corporate giant that uses artificial intelligence and machine learning to detect and punish people who “game” its system.
That's the nature of the beast!
And if you're going to come up against such a beast with bad weapons or fight in a sloppy way, the chances of you losing are quite high.
But if you go with well-crafted tools, your chances of success are much better.
So I would focus on well-built PBNs—these are made from the carcasses of previously high-flying, even branded, websites.
For whatever reason, they’ve gone belly up, and their domains have been snapped up by PBN builders.
You can't tell when you load up these domains because they look 100% legit and get organic traffic.
Start with those PBNs if you are looking for better results.