Final update, that marks this post as solved.
I read this post ([HowTo] Enable and configure hibernation with BTRFS) and followed the instructions. After a few attempts i was successfully able to hibernate my laptop.
Somehow, the script did not worked for me. But following the instructions carefully did. In my first attempts i used the wrong UUID. The mkswap tool returns a UUID after succesfully creating a swap. But that UUID is not to be used for the resume kernel parameter. I had to use the UUID that is returned by findmnt.