I solved the issue and regained my space back! Hallelujah !
I have 2 apple IDs since the iTunes times. I'm sharing my storage with my family that is composed by
Apple ID 1 me
Apple ID 2 me-itunes
My Husband
I need to share it with myself because Apple doesn't let me merge the two accounts without losing all my purchases
from music, movies to apps and subscriptions
I logged out of iCloud-signed in with the usual Apple ID 1 and I used the Apple ID 2 instead, to login
This my first time ever to log-in with this Apple ID 2 in iCloud , I always thought that the other email I use for iCloud is the only ONE
Probably don't ask me why, Apple or an iCloud bug assigned the 50GB to my second ID 2
Deleting it from the first Apple ID 1, let me delete it but it needed the approval from the second ID to give me back the storage space 😵💫
Login in iCloud using my Apple ID 2 me-itunes showed me 50GB in use even if everything was 0 KB
I logged out of iCloud on one old device and logged back in with the Apple ID 2 me-itunes
In that moment the 50Gb space magically dissolved , yeah!
I hope this could help someone else having to deal with the storage craziness.
Edited to try to give a little more sense to the messy issue