A broad core update is rolled out by Google on the 3rd of June 2019. These updates are basically aimed at improving Google's understanding regarding web page and search queries. Read more at searchenginejournal.com
Whenever google make broad changes to their core algorithm, they inform about these because there is nothing in particular to fix, and they don’t want content owners to mistakenly try to change things that aren’t issues.
The reason they say there is nothing to fix is because core algorithm updates may not generally be about targeting specific kinds of low quality content but rather, about improving relevance.
These kinds of updates are about improving how Google understands search queries, improving how Google understands web pages and bringing both sides together to provide more relevant search results.