Is pbn is legal or illegal

PBN is absolutely illegal in the eyes of Google. Because you give authority to the new site from your own Private Blog Network. Which is absolutely wrong. But many bloggers still rank their site quickly with the help of this and earn money.

So if you have complete knowledge of PBN, then only work on this thing. Because once Google caught you. So Google can downgrade, ban and penalty your website and your website will never rank in future.