PC immediately powers on after hibernation

Hi everyone, I'm starting a new thread here since all I've found is at least 2 years old. Hope that's fine.

The issue as the topic title says is that my PC immediately powers on after hibernation.
This has not always been the case, but since I'm dealing with it for over a year now I can't remember what changes I made.

There are so many threads and posts here and on the web, but I'd like some "individual" help here before I try out those thousands of guides.

First of all, how can I contribute, what information should I post here in order to get more help?

Many thanks in advance