Peace first.

Then, I indeed noticed it ! I was not understanding why my TOR browser, who showing a message on top, after reading it, it was saying that Twitter was available through .onion too :)

I don't use TOR but if I did somehow I don't think I'd visit Twitter. Aren't they polar opposites on the privacy range?

I suspect there's often a misunderstanding about this. Access to the twitter service on this can sometimes be valuable in regions where access to the mainstream is limited or entirely restricted.