Three Steam Sale Dates Leak?

A tweet from the Steam Database posts what they say are the dates for the next three Steam sales. They say these come from multiple sources ignoring Valve's hopes for a degree of confidentiality that these sales almost never enjoy. That said, none of this is officially confirmed:
Leaked upcoming @steam_games 2019 sale dates:

🎃 Halloween Sale: October 28 - November 1
🍂 Autumn Sale: November 26 - December 3
🎅 Winter Sale: December 19 - January 2

Multiple developers posted it in multiple places despite Valve asking otherwise. But you know how that goes.