Are you guy seeing serp fluctuations too? ...Algo update?

Are your sites in a specific industry or a mix? Ours are mostly in the service industry US-based.

No, there are no official core updates, changes, bugs or glitches confirmed by Google as of this writing.


Edit: Mike Friedman discovered it is a glitch. Thanks Mike.


However, there are two updates that were implemented in the past and have reached the point of "emphasis" (unannounced changes) pertaining to Mobile-First Indexing and SSL Indexing.

Mobile-First emphasis officially starts September 2020. Emphasis affecting malformed sites may have unofficially started. Hence the August 6, 2020 Lighting Talk.
Announcing mobile first indexing for the whole web
Thursday, March 05, 2020
Side note: I believe the first announcement was September 2019 and alerted webmasters that August 2020 was the cutoff date.

SSL Indexing. There is a Google SSL requirement that many already know of and both your mobile-first pages and the desktop pages must be accessible for indexing. Very similar to mobile-first requirements.

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Transcript Lighting Talk Aug 6 2020
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MARTIN SPLITT: Hello, and welcome
to the Webmaster Conference Lightning Talk series.
This time, we will talk about mobile-first indexing.

As many of you may already know, mobile-first indexing
is an ongoing effort by Google for several years.
So what is mobile-first indexing, exactly?
Let's look at how Google indexing works.
First, Googlebot will crawl URLs from your site
with the desktop and mobile user agent.
With the original desktop-first indexing,
the indexing system will get the page information
from the desktop page content.
Finally, the page will be shown in the search results
if the information has enough relevance for user queries.
With mobile-first indexing, the indexing system
will look at the mobile page instead of the desktop page
for information.
Well, now that we know the difference between desktop-
and mobile-first indexing, what challenges
can occur where there's mobile-first indexing
on your site?
One possibility is that something's
going wrong when we crawl with the mobile Googlebot.
The request might be treated differently by your server
based on the user agent, or something else
might be going wrong when making a request to the mobile pages.
Then if that happens, there will be little to no information
that we can get from your pages.
And if that happens, we can't get
the necessary signals to show your page in the search
results.
Another possibility is that your mobile page
is having content issues.
We might get less or maybe even incorrect
information from your page, which
results in us getting less information about the page's
relevance.
Both situations will prevent Google
from serving your site well when your site is enabled
for mobile-first indexing.
Now, that is something that you probably want to avoid.
So how can you avoid issues like that?
For example, you may have put the following rule
in robots.txt under your mobile site.
It tells Google about not to crawl pages
under your mobile version.
Or if you add any of these meta tags on your mobile pages,
they tell Googlebot not to index these pages.
Those settings will prevent Googlebot
from either crawling or indexing these pages,
so please don't set any of the mobile pages you
expect to appear in Google Search up like that.
For another example, if you put the following rule
in robots.txt under your resources host,
it tells Google not to crawl any files under mobile-css.
If you add any of these meta tags on the mobile pages,
they would tell Googlebot not to follow any of the links
on these pages.
Those settings will prevent Googlebot
from crawling the resources.
If you let Googlebot crawl resources
for your desktop page, you should probably
also let it crawl them for your mobile page.
Otherwise, it cannot understand your mobile page as well
as your desktop page.
To conclude, for mobile crawl issues,
you need to check your robots.txt files,
and you also want to be careful with noindex and nofollow tags
for indexing issues.
Please also check if your hosts have enough crawl capacity
to handle as many mobile crawls as they handle desktop crawls.
Setting mobile-page content correctly
is as important as setting the mobile crawler correctly.
Our general suggestion is to make
sure your primary content is the same
on desktop and mobile versions.
Let's look at some cases where it might not be the same.
Let's say you have a desktop page that
looks like this with several images, and some text.
But then you make your mobile version look
like this with only two images and very few text.
Users need to click the Plus button to let
the rest of the page load.
However, Googlebot won't click the button to load them,
so all of the unloaded information
is invisible to Google.
And a special note--
if it's your intention to have less
content on the mobile page, please be aware
that Google might not be able to serve your site as well as
before mobile-first indexing.
That is because we cannot get the full information from
your site as we did before.
Headings are also important for Googlebot
to understand your page.
This is a good example of a heading.
It uses the good old h1 tag.
Well, this is not a good example.
Regardless of its class, Googlebot
will treat it as if it is normal text rather than a heading.
It will then affect how Googlebot understands the page.
So don't forget to use semantic heading tags
on your mobile pages.
If you also care about image and video traffic of your site,
you need to do some extra checks for them.
For example, this is a good example
on how to define an image, while this is not.
Because the alt text is empty, it
will be a bad experience for some users.
Neither is this one because the alt text is not meaningful.
People don't know what the image is about just
looking at the alt text.
So please don't do that.
Also, don't do it this way either.
That's not even a semantic image tag.
Googlebot cannot index CSS images like that.
For images and videos, another important thing
is to check their position on the page.
Let's say you have a desktop page like this,
with the video as an easy-to-see position,
while on the mobile page, you put
an ad on the top of the page like this.
Users need to scroll down a lot to finally see the video here.
Imagine what they will feel like if they were only
searching for the video.
So please don't let your mobile pages have such a bad user
experience.
Finally, it is better to do some extra checks
for invisible parts of your page.
They won't affect user experience,
but they will affect how Googlebot understands them.
One such example of an invisible part of the page
is structured data.
We suggest you keep structured data the same
on desktop and mobile pages.
The other one are meta descriptions.
Please don't forget to add them to your mobile pages.
They matter a lot for Googlebot as well.
If you want to learn more about mobile-first indexing,
check out the video description for more information,
and follow us on Twitter @GoogleWMC to stay
tuned with more on the journey to mobile-first indexing.
Thank you very much for watching.
Have a great day.