The Google dance
Welcome to one of the most annoying (and exciting) aspects of SEO, the Google Dance.
When Google is trying to determine what position to eventually place your new asset (website, webpage, etc.) on its index, it experiences a lot of volatility.
Simple as that.
Google Dance occurs when your page is starting to be noticed by Google and is given a chance to appear in SERPs (SERP = Search Engine Results Page).
Imagine Google approaching me and saying, “Show me your moves!”
As a practical matter, this means that your newly published page will be moved up overnight from a very low position in Google (maybe 100?) so that Google can see what users think.
Google considers social signals when determining where to rank a page, including whether or not users visit, spend time on, and enjoy the content of your page.
The way Google does this is to change the ranking of your page (without affecting other ranking factors) just to see what happens.