Images larger than 500 KB can affect how fast your page loads for users, specially if there is more than one image on the page. Users who have a limit on their internet download will also be less inclined to use your website since it will needlessly use up their allowed downloads.
As of May 2020 Google has announced that it will be incorporating Core Web Vitals in their search engine result rankings. One of the areas of measurement for Core Web Vitals is Largest Contentful Paint (LCP).
LCP looks at how long it takes for the largest content element to be loaded into the page. Google has also noted that images typically are one of the largest elements on a page. As such the images used directly on the page as well as a background image is taken into account when calculating LCP. For this reason it is recommended to avoid large image sizes so as not to lower your LCP score.
How can I resolve this issue?
Change the image you have used to one that is smaller than 500 KB. If you have an image editor such as GIMP or Photoshop you could look to optimize the resolution of your image for web use.
A known exemption to this rule is when you have an image gallery in your website that are specifically for photographers to use for printing material about your website since printed images require larger sizes.
What topics do this checkpoint affect?
Can you explain how this checkpoint works?
The checkpoint reviews the file size of images and flags all images that are larger than 500 KB