Maintenance for the week of January 12:
• [COMPLETE] ESO Store and Account System for maintenance – January 13, 9:00AM EST (14:00 UTC) - 12:00PM EST (17:00 UTC)
• ESO Store and Account System for maintenance – January 14, 9:00AM EST (14:00 UTC) - 12:00PM EST (17:00 UTC)
That usually pops up only a day or two before, and has traditionally been a bundle with a unique mount and a bunch of starter consumables like XP scrolls.
It's usually not a sale on the game or DLCs or Crowns; those go on sale for the holidays a month later.
They're having a sale on the DLCs right now (unless it's ended), so that's sort of like a Black Friday sale, except it isn't during Black Friday. It seems like many stores and companies have started doing that in recent years, having "Black Friday" sales that start before Black Friday and/or last after Black Friday.