It seems a bit false to call it a hoax: - first, the locations he amazingly manages to find with Google Street View and Earth are actually in Venice or in it's district - second, as pointed out by a response on twitter, Reuters interviewed a resident there about that matter, so they most likely were there and would not post about it if it was not true

Reuters tweet here: https://twitter.com/reuters/status/1240242797933821955?s=21

I think the hoax is that people were saying it was a hoax. Which blows my mind a little. That was the take I originally believed.

This will blow your mind in a similar way: https://journals.sagepub.com/doi/full/10.1177/03063127145356...

1) Algae in water suddenly dissapear

2) in the previous weeks everybody was cleaning the streets with lots of diluted bleach

Mhh... I sense some connection here, and is not what they think...

So it's not a hoax.