Google has released a broad core algorithm update on Monday June 3rd, 2019. It was announced a day before, through the official Google SearchLiaison Twitter account:
As usual after such updates, Google recommends not to take any sudden actions and just keep being focused on "building great content", sending their followers to their posts from October 2018 for more information on writing good quality content.
I has been confirmed by Google that there has been a major quality update performed. The update took place throughout a period of one week, but the peak was detected around August 1st and 2nd. A lot of websites were strongly affected. As for now, Google recommends not to take any sudden moves and just keep being focused on "building great content".