Each year, Google’s search algorithm changes thousands of times. The SERPs are consistently shifting and your site’s performance can fluctuate.
A handful of times per year, Google rolls out larger updates, often referred to as “broad core algorithm updates” (that is, until a cool nickname is given like Panda or Penguin). These updates are larger and tend to impact sites across a variety of industries. For example, back in January 2020, there was the Featured Snippet update that impacted any site that owns a rich snippet.