Valve sent out a email to it’s partners on Monday evening informing them that there is an upcoming Steam Sale.
The event occurs between January 23rd and January 27th 2020 (inclusive)
They also state the following:
Please remember that it is not possible to submit a discount within 30 days of the following: Releasing a game for the first time at full price OR the end of new release launch discount OR a price increase. This limitation applies to all discounts, including seasonal sale events.Steam announcement sent to partners