I've run a GTmetrix test on my website.
I get one issue in its audit report at https://gtmetrix.com/reports/www.datanumen.com/3FtNGzq8/
I check the image with Chrome DevTools, as below:
Since the test is for Desktop, the image size is 649 x 508 and it is served as 649 x 508.
Also I found that there is a
srcset tag in the code for the different resolutions, which is also recommended in https://gtmetrix.com/blog/how-to-properly-size-images/. So I cannot find the problem with the image, why does GTmetrix report it as an issue?