There may have been a Google search ranking algorithm update on the smaller side on or around October 26th. There was both some limited chatter on that day, limited in that is was more than the norm but less than a huge update. And many of the tools showed elevated volatility on or around October 26th.
The ongoing WebmasterWorld thread had chatter start around October 26th with complaints of ranking shifts in Google Search. Here is some of that chatter:
Traffic was higher and more stable for a while, until today. A jump up in rank is coinciding with a big drop in traffic from all english language countries. Search down 25% at 3pm and direct down 38%. I am not bothering to spend time investigating whether it's because of page layout or # of ads on the page...Google will do what it's going to do and so will I.
We are having one of the most volatile months in terms of (unannounced) updates and serp fluctuations but one of the least active monthly threads.
For the past few days, new posts are not getting indexed, GSC is showing Discovered, but not indexed. sad It's a 5-year-old website with 1M impressions daily(100K organic traffic). Unique content, +1K words, but still...not indexed. SAD!
No, high authority websites were never downranked in my niche until very recently, hence the major shuffle remark.
Again, not a flood of complaints but a number of them that is higher than the norm. And we had a very quiet weekend, which again, is not in the recent norm.
Here are what the tools are showing:
Have you noticed ranking changes yesterday?
Forum discussion at WebmasterWorld.