Thanks for your help.
In the end, with some effort and a lot of descaling product, I was able to release the gas hose.
To say that my doubts arose when, despite doing what I thought was correct, it was not possible for me to loosen the nut, and even less so, when according to what I read in a few posts above, interpreting that the thread tightened to the left, what he did that will change my way of proceeding.
Finally, I can say, for those who may be interested, that the thread tightens to the right, so to loosen it, you have to turn to the left.