Product review

It means that after a story is developed and tested, the PO have to give a final approval by check the feature on testin environment or by developer / QA.

If that is the case, it means the item is not Done until the PO has performed some work. The PO is therefore also one of the Developers, and the work he or she is doing ought to be reflected in the Definition of Done which is their joint commitment.

There is nothing in the Scrum framework that mentions this.  This is a process step that your past organizations chose to have.  The Scrum framework will work with any process as long as that process does not change any of the framework's events, artifacts or values.  

So, what do you say about this process? Is it a known process? If so, can you find me some references / tutorials?

Is it bad process? 

It is known and there are probably mentions of similar processes in these forums.  As for explicit references or tutorials, I wouldn't even begin to know where to look.  This isn't something that I know of as being defined or recommended by any process or methodology I have ever used or studied. 

Is it bad?  That all depends on whether the organization is getting benefit from it and if it is allowing them to deliver value to their stakeholders.  You would need to ask your stakeholders and team members that question to get an accurate answer.