In 2016 Google sent out a batch of new manual penalty notices that mostly hit bloggers. Bloggers were penalized for accepting free products in exchange for a review with a link to merchant’s website or accepting paid reviews with such links.
It’s a well known fact for years now that Google doesn’t like to see paid reviews or reviews paid through free product or free service pass PageRank.
Online stores who were buying lots of links that pass PageRank would get hit by a manual penalty or even worse, by the Penguin algorithm.
Google now decided to focus on those who enable merchants to get such links – the bloggers. So Google sent out manual penalties to bloggers who didn’t listen to this guideline.
Impact can be both positive and negative, depending on how good you were in obeying Google’s guidelines in past. Till now, if you only obtained a few links with this method where you give a free product or pay for review to a blogger, Google would be unable to figure out that you’re doing something wrong on a massive scale and you wouldn’t get penalized in any way.