During the English Google SEO Office-Hours From November 26, 2021, Google’s John Mueller read aloud a question about something that happens when Google updates its algorithms:
“During the core update period, do you carry out the same updates as on regular days? If the changes in the core updates are subtle, it’s indistinguishable from regular updates.”
John’s response (edited for clarity) was:
“I don’t think we hold back on normal updates during these times. The core updates usually take…a week or so to be rolled out.
“And the normal updates: we tend not to hold them back during that time, because we make lots of updates over the course of time.
“The things we would hold back a little bit are maybe other bigger updates that we want to let people know about. So essentially, if we have some bigger update involving structured data that we want to talk about, then probably we’ll try to hold that back a little bit, so that it’s not like one update after another, but more kind of like…we can talk about the update a little bit clearer, and make it a little bit easier for people to understand what exactly is changing.
“But the kind of the normal updates that we do all the time, like shifting the UIs slightly by a couple of pixels, changing colors or things like that, those are all updates that we can do independently.”
So, in short, when Google updates its algorithms, there are other, smaller updates going on, unless those other ones are significant, in which case, Google may want to let people know about them.