I dropped out of being a technical reviewer for Packt after they declined my suggestions about things that were factually wrong, because that's not what they wanted me to review.
They never fixed the many factual inaccuracies before it went to print.
I found Packt books to often be of rather poor quality, and I'm now avoiding things published by them. Manning is slightly better, but not that much. I'd consider both brands to be rather poor at reviewing and editing.
This does not surprise me. In the book I reviewed there were a lot of simplistic explanations that lacked nuance. Even if that's the right level for their target market, I think it could have been done in a better way, giving the reader the push to go and research in more depth if they so wish, but to be honest I'm not sure the author was at that level.
They never fixed the many factual inaccuracies before it went to print.