You’ll see this error or warning in Google Pagespeed Insights when the biggest image or piece of content was lazy loaded.
We want to avoid this if possible as lazy loading the biggest image on the page will increase your LCP (largest contentful paint) timing.
In a nutshell, lazy loading slows down image load times when the image is in the viewable area of the screen when the page first loads.
We definitely want to keep lazy loading, we just don’t want the above the fold images lazy loaded.
There’s several different techniques to solve this and lazy loading above the fold images impacts both FCP (first contentful paint) and LCP (largest contentful paint) negatively.
Here’s two articles that explain in detail how we solve this issue: