We have some URLs that are being flagged as poor inside Search Console in the Web Core Vitals report. For example, the report is saying that some pages have too many CLS issues. When looking into things we can do to update we have noticed that when we run the same page using the PageSpeed Insights tool we are not getting the same bad scores. This is making it hard for us to actually know what needs to be addressed. Nor can we tell if a change actually fixed the issue because in PageSpeed Insights there is not an issue.  Has anyone else had similar issues. If so have you found a way to fix it?

For sever work- load enhancements we are planning to move our images to a sub-domain. so the files would be located at something like images.domain.com Rather than domain.com/images/ We are a large Ecommerce site so we have a lot of images. These will be self hosted so we are not using a CDN. I'm hoping someone has done the same and if there were any steps they had wished they had taken before making the move/ if they noticed any traffic impacts things like that.