In early June 2019, Google launched two updates to their algorithm. The major update was rolled out from June 3rd to June 8th which coincided with the diversity update rolled out from June 4 - June 6th.
Diversity update: Google wants to diversify the domains that are appearing in SERPs
Core Algorithm update: The core algorithm update also led to fluctuations in rankings across many businesses. What experts say is that the core update devalued older pages on websites.