Hello again,
Found it! Today I leaned the bike on the side for about 5 minutes and, as you can see in the attached picture, liquid started to drip on the side fairing. The smell made it obvious seconds later, it was gasoline.
It looks very oily on the ground and the old stain does not smell at all, but now I am 100% sure that it's gasoline. Even if initially I suspected that some brake fluid might have come out between elements 2 and 3 of the picutre greywolf posted, I'm happy to say I'm glad I was wrong.
If possible can someone edit the title, not to confuse others?
Thank you all! Sorry was wasting your time.